The chemotaxis process that directs the migration of an axon growth cone to a specific target site in response to a combination of attractive and repulsive cues.

The process involved in the specification of cell identity. Once specification has taken place, a cell will be committed to differentiate down a specific pathway if left in its normal environment.

The process involved in the specification of cell identity. Once specification has taken place, a cell will be committed to differentiate down a specific pathway if left in its normal environment.

The morphogenetic process in which the anatomical structures of the compound eye are generated and organized. The adult compound eye is a precise assembly of 700-800 ommatidia. Each ommatidium is composed of 20 cells, identified by cell type and position. An example of compound eye morphogenesis is found in Drosophila melanogaster.

Any process that activates or increases the rate of neuroblast proliferation.

A response to protect an organism from a directly detected or perceived external threat from an insect or insects to that organism.

Any process that modulates the frequency, rate or extent of glycolysis.

A process that is carried out at the cellular level which results in the assembly, arrangement of constituent parts, or disassembly of cytoskeletal structures comprising actin filaments. Includes processes that control the spatial distribution of actin filaments, such as organizing filaments into meshworks, bundles, or other structures, as by cross-linking.

A series of molecular signals initiated by the binding of an extracellular ligand to the receptor Notch on the surface of a target cell, and ending with regulation of a downstream cellular process, e.g. transcription.

A series of molecular signals initiated by the binding of an extracellular ligand to the receptor Notch on the surface of a target cell, and ending with regulation of a downstream cellular process, e.g. transcription.

A series of molecular signals initiated by the binding of an extracellular ligand to the receptor Notch on the surface of a target cell, and ending with regulation of a downstream cellular process, e.g. transcription.

Construction of a stage-1 egg chamber in the anterior part of the germarium, from the progeny of germ-line and somatic stem cells. An example of this is found in Drosophila melanogaster.

Construction of a stage-1 egg chamber in the anterior part of the germarium, from the progeny of germ-line and somatic stem cells. An example of this is found in Drosophila melanogaster.

The directed movement of an ovarian follicle cell that takes place during oogenesis. During egg chamber formation, follicle cells migrate to envelop the germ-line cysts and move in between cysts. At stage 10B, follicle cells migrate centripetally between the nurse cells and the oocyte, enclosing the anterior of the egg. An example of this is found in Drosophila melanogaster.

The directed movement of a border cell through the nurse cells to reach the oocyte. An example of this is found in Drosophila melanogaster.

Polarization of the oocyte along its anterior-posterior axis. An example of this is found in Drosophila melanogaster.

Any process that modulates the rate or extent of progress through the mitotic cell cycle.

The process during Drosophila embryogenesis whereby the ectodermal cells of the lateral epithelium stretch in a coordinated fashion to internalize the amnioserosa cells and close the embryo dorsally.

The process whose specific outcome is the progression of the ectoderm over time, from its formation to the mature structure. In animal embryos, the ectoderm is the outer germ layer of the embryo, formed during gastrulation.

The cell fate determination process in which a cell becomes capable of differentiating autonomously into a neuroblast cell regardless of its environment; upon determination, the cell fate cannot be reversed. An example of this process is found in Mus musculus.

The cell fate determination process in which a cell becomes capable of differentiating autonomously into a neuroblast cell regardless of its environment; upon determination, the cell fate cannot be reversed. An example of this process is found in Mus musculus.

The cell fate determination process in which a cell becomes capable of differentiating autonomously into a glial cell regardless of its environment; upon determination, the cell fate cannot be reversed.

The expansion of a neuroblast population by cell division. A neuroblast is any cell that will divide and give rise to a neuron.

The process whose specific outcome is the progression of the ventral cord over time, from its formation to the mature structure. The ventral cord is one of the distinguishing traits of the central nervous system of all arthropods (such as insects, crustaceans and arachnids) as well as many other invertebrates, such as the annelid worms.

The process whose specific outcome is the progression of the peripheral nervous system over time, from its formation to the mature structure. The peripheral nervous system is one of the two major divisions of the nervous system. Nerves in the PNS connect the central nervous system (CNS) with sensory organs, other organs, muscles, blood vessels and glands.

The process whose specific outcome is the progression of sensory organs over time, from its formation to the mature structure.

The process in which the anatomical structures of the foregut are generated and organized.

The increase in mass of imaginal discs by cell proliferation prior to metamorphosis. Imaginal discs are epithelial infoldings in the larvae of holometabolous insects that develop into adult structures (legs, antennae, wings, etc.) during metamorphosis from larval to adult form.

The regionalization process that results in defined areas of the imaginal disc that will undergo specific cell differentaiton. Imaginal discs are epithelial infoldings in the larvae of holometabolous insects that develop into adult appendages (legs, antennae, wings, etc.) during metamorphosis from larval to adult form.

The establishment, maintenance and elaboration of the dorsal/ventral axis of the imaginal disc. Imaginal disks are masses of hypodermic cells, carried by the larvae of some insects after leaving the egg, from which masses the wings and legs of the adult are subsequently formed.

Formation and/or maintenance of a lineage boundary between dorsal and ventral compartments that cells cannot cross, thus separating the populations of cells in each compartment.

The process in which the anatomical structures derived from the eye-antennal disc are generated and organized. This includes the transformation of an eye-antennal imaginal disc from a monolayered epithelium in the larvae of holometabolous insects into recognizable adult structures including the eye, antenna, head capsule and maxillary palps.

The process in which the R3/R4 photoreceptors commit to their cell fate. R3 and R4 are paired photoreceptors which contribute the outer rhabdomeres.

The establishment, maintenance and elaboration of the proximal/distal axis of the wing disc, a precursor to the adult wing.

The regionalization process in which the area of a imaginal disc-derived wing that will form a wing vein is specified.

The process in which the anatomical structures of the imaginal disc-derived wing are generated and organized. The wing is an appendage modified for flying.

The process in which the anatomical structures of the imaginal disc-derived wing are generated and organized. The wing is an appendage modified for flying.

The process in which the anatomical structures derived from the leg disc are generated and organized. This includes the transformation of a leg imaginal disc from a monolayered epithelium in the larvae of holometabolous insects into recognizable adult structures including the leg, coxa and ventral thoracic pleura.

The process whose specific outcome is the progression of the mesoderm over time, from its formation to the mature structure. The mesoderm is the middle germ layer that develops into muscle, bone, cartilage, blood and connective tissue.

The developmental sequence of events leading to the formation of adult skeletal muscle tissue. The main events are: the fusion of myoblasts to form myotubes that increase in size by further fusion to them of myoblasts, the formation of myofibrils within their cytoplasm and the establishment of functional neuromuscular junctions with motor neurons. At this stage they can be regarded as mature muscle fibers.

The cell fate determination process in which a cell becomes capable of differentiating autonomously into a muscle cell regardless of its environment; upon determination, the cell fate cannot be reversed.

The memory process that deals with the storage, retrieval and modification of information a long time (typically weeks, months or years) after receiving that information. This type of memory is typically dependent on gene transcription regulated by second messenger activation.

The memory process that deals with the storage, retrieval and modification of information a long time (typically weeks, months or years) after receiving that information. This type of memory is typically dependent on gene transcription regulated by second messenger activation.

The process in which the migration of an axon growth cone of a motor neuron is directed to a specific target site in response to a combination of attractive and repulsive cues.

Any process that activates or increases the rate or extent of cell proliferation.

The control of viability and duration in the adult phase of the life-cycle.

The orderly movement of a glial cell, non-neuronal cells that provide support and nutrition, maintain homeostasis, form myelin, and participate in signal transmission in the nervous system.

The asymmetric division of cells to produce two daughter cells with different developmental potentials. It is of fundamental significance for the generation of cell diversity.

The process in which the anatomical structures of the chaeta are generated and organized. A chaeta is a sensory multicellular cuticular outgrowth of a specifically differentiated cell.

The process in which the anatomical structures of the imaginal disc-derived wing margin are generated and organized. The wing margin is a strip of cells in the third instar disc at the boundary between the presumptive dorsal and ventral surfaces of the wing blade.

Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a stimulus from a symbiont, an organism living with an organism of a different species in close physical association. The symbiont is defined as the smaller of the organisms involved in a symbiotic interaction.

The establishment, maintenance and elaboration of the dorsal/ventral axis. The dorsal/ventral axis is defined by a line that runs orthogonal to both the anterior/posterior and left/right axes. The dorsal end is defined by the upper or back side of an organism. The ventral end is defined by the lower or front side of an organism.

The regionalization process in which specific areas of cell differentiation are determined along the anterior-posterior axis. The anterior-posterior axis is defined by a line that runs from the head or mouth of an organism to the tail or opposite end of the organism.

The process in which a relatively unspecialized cell acquires the specialized features of a glial cell.

Any process that increases the frequency, rate or extent of gene expression. Gene expression is the process in which a gene's coding sequence is converted into a mature gene product or products (proteins or RNA). This includes the production of an RNA transcript as well as any processing to produce a mature RNA product or an mRNA or circRNA (for protein-coding genes) and the translation of that mRNA or circRNA into protein. Protein maturation is included when required to form an active form of a product from an inactive precursor form.

Any process that increases the frequency, rate or extent of gene expression. Gene expression is the process in which a gene's coding sequence is converted into a mature gene product or products (proteins or RNA). This includes the production of an RNA transcript as well as any processing to produce a mature RNA product or an mRNA or circRNA (for protein-coding genes) and the translation of that mRNA or circRNA into protein. Protein maturation is included when required to form an active form of a product from an inactive precursor form.

Any process that decreases the frequency, rate or extent of gene expression. Gene expression is the process in which a gene's coding sequence is converted into a mature gene product or products (proteins or RNA). This includes the production of an RNA transcript as well as any processing to produce a mature RNA product or an mRNA or circRNA (for protein-coding genes) and the translation of that mRNA or circRNA into protein. Protein maturation is included when required to form an active form of a product from an inactive precursor form.

The process aimed at the progression of a neuroblast over time, from initial commitment of the cell to a specific state, to the mature neuroblast. It does not include processes where the neuroblast turns into a glial cell or a neuron.

A discrete cell cycle in the third instar eye imaginal disc after progression of the morphogenetic furrow that contributes to compound eye morphogenesis. It is essential for generation of a sufficient pool of uncommitted cells to develop complete ommatidia.

A discrete cell cycle in the third instar eye imaginal disc after progression of the morphogenetic furrow that contributes to compound eye morphogenesis. It is essential for generation of a sufficient pool of uncommitted cells to develop complete ommatidia.

The process in which the anatomical structures of a follicular epithelium are generated and organized.

The process in which the anatomical structures of an imaginal disc-derived leg joint are generated and organized. The leg joint is a flexible region that separates the rigid sections of a leg to allow movement in a controlled manner. An example of this is found in Drosophila melanogaster.

The process in which a cell becomes capable of differentiating autonomously into a sensory organ precursor cell regardless of its environment; upon determination, the cell fate cannot be reversed.

The process whose specific outcome is the progression of a chaeta over time, from its formation to the mature structure. A chaeta is a sensory multicellular cuticular outgrowth of a specifically differentiated cell.

The process in which relatively unspecialized cells, e.g. embryonic or regenerative cells, acquire specialized structural and/or functional features that characterize the cells, tissues, or organs of the mature organism or some other relatively stable phase of the organism's life history. Differentiation includes the processes involved in commitment of a cell to a specific fate and its subsequent development to the mature state.

The process that occurs during oogenesis involving the ovarian follicle cells, somatic cells which surround the germ cells of an ovary. An example of this is found in Drosophila melanogaster.

The process that occurs during oogenesis involving the ovarian follicle cells, somatic cells which surround the germ cells of an ovary. An example of this is found in Drosophila melanogaster.

Formation of a single follicular epithelium around the germ-line derived cells of a cyst formed in the germarium. An example of this process is found in Drosophila melanogaster.

Development of ovarian follicle cells to create the interfollicular stalks that connect the egg chambers of progressive developmental stages. An example of this process is found in Drosophila melanogaster.

Development of ovarian follicle cells to create the interfollicular stalks that connect the egg chambers of progressive developmental stages. An example of this process is found in Drosophila melanogaster.

Any process by which an organism or tissue maintains a population of germ-line stem cells.

Directed movement of the oocyte, following its specification, from its original central position in the cyst to a posterior position relative to the nurse cells of the egg chamber, and its maintenance in this posterior location. This is the first sign of anterior-posterior asymmetry in the developing egg chamber.

Allocation of epithelial cells within each migrating branch in an open tracheal system to distinct tracheal cell fates. During the migration phase each branch forms a well-defined number of cell types (including fusion cells, terminal cells and branch cells) at precise positions.

The stages of blood cell formation that take place within the embryo.

The process in which an embryonic mesoderm-derived hemocyte precursor cell acquires the specialized features of a crystal cell. Crystal cells are a class of cells that contain crystalline inclusions and are involved in the melanization of pathogenic material in the hemolymph.

The production of blood cells from the larval lymph gland. The lymph gland consists of three to six bilaterally paired lobes that are attached to the cardioblasts during larval stages, and it degenerates during pupal stages.

The process in which a relatively unspecialized hemocyte precursor cell acquires the specialized features of a lamellocyte. Lamellocytes are a hemocyte lineage that exists only in larvae, but are seldom observed in healthy animals. Lamellocytes differentiate massively in the lymph glands after parasitization and are large flat cells devoted to encapsulation of invaders too large to be phagocytosed by plasmatocytes.

The multiplication or reproduction of hemocytes, resulting in the expansion of the cell population. Hemocytes are blood cells associated with a hemocoel (the cavity containing most of the major organs of the arthropod body) which are involved in defense and clotting of hemolymph, but not involved in transport of oxygen.

Any process that stops, prevents, or reduces the frequency, rate or extent of lamellocyte differentiation. Lamellocytes differentiate massively in the lymph glands after parasitization and are large flat cells devoted to encapsulation of invaders too large to be phagocytosed by plasmatocytes.

Progression of the eye-antennal imaginal disc over time, from its initial formation through to its metamorphosis to form adult structures including the eye, antenna, head capsule and maxillary palps.

The process giving rise to the pattern of cell differentiation in the wing imaginal disc.

Division of an imaginal disc-derived leg into a series of semi-repetitive parts or segments. The Drosophila leg, for example, has nine segments, each separated from the next by a flexible joint.

The process by which an organism or tissue maintains a population of female germ-line stem cells.

Any biological process involved in the maintenance of the steady-state number of intestinal stem cells within a population of cells.

Any process that modulates the frequency, rate or extent of the growth of all or part of an organism so that it occurs at its proper speed, either globally or in a specific part of the organism's development.

Any process that modulates the frequency, rate or extent of the growth of all or part of an organism so that it occurs at its proper speed, either globally or in a specific part of the organism's development.

The specification of polarized ommatidia. Ommatidia occur in two chiral forms. The trapezoidal arrangement of photoreceptors in the dorsal part of the eye is the mirror image of that in the ventral part.

The specification of polarized ommatidia. Ommatidia occur in two chiral forms. The trapezoidal arrangement of photoreceptors in the dorsal part of the eye is the mirror image of that in the ventral part.

The process in which the cone cells of the compound eye, the lens-secreting cells in the ommatidia, adopt pathways of differentiation that lead to the establishment of their distinct cell type.

Any process that mediates the specification of a cell into a cardioblast. A cardioblast is a cardiac precursor cell. It is a cell that has been committed to a cardiac fate, but will undergo more cell division rather than terminally differentiating.

The process in which a hemocyte precursor cell acquires the characteristics of a crystal cell, a class of cells that contain crystalline inclusions and are involved in the melanization of pathogenic material in the hemolymph.

Any process that modulates the frequency, rate or extent of crystal cell differentiation.

Any process that activates or increases the frequency, rate or extent of crystal cell differentiation.

Any process that activates or increases the frequency, rate or extent of cell death of neurons by apoptotic process.

The process in which a specialized cell loses the structural or functional features that characterize it in the mature organism, or some other relatively stable phase of the organism's life history. Under certain conditions, these cells can revert back to the features of the stem cells that were their ancestors.

Any process that stops, prevents, or reduces the frequency, rate or extent of compound eye photoreceptor development.

The process in which a relatively unspecialized cell acquires the specialized features of the R7 photoreceptor.

The process in which a relatively unspecialized cell acquires the specialized features of the R7 photoreceptor.

Any process that modulates the frequency, rate or extent of cell differentiation, the process in which relatively unspecialized cells acquire specialized structural and functional features.

Any process that activates or increases the frequency, rate or extent of cellular DNA-templated transcription.

Any process that activates or increases the frequency, rate or extent of transcription from an RNA polymerase II promoter.

Any process that stops, prevents, or reduces the frequency, rate or extent of signal transduction mediated by the JNK cascade.

Signaling between cells of equivalent developmental potential that results in these cells adopting different developmental fates. An example is the suppression by cells with a particular fate of the adoption of the same fate by surrounding cells.

Signaling between cells of equivalent developmental potential that results in these cells adopting different developmental fates. An example is the suppression by cells with a particular fate of the adoption of the same fate by surrounding cells.

Programmed cell death that occurs in the developing retina.

Programmed cell death that occurs in the retina to remove excess cells between ommatidia, thus resulting in a hexagonal lattice, precise with respect to cell number and position surrounding each ommatidium.

The cellular homeostatic process that preserves a muscle cell in a stable functional or structural state.

Establishment of the dorsal filaments, elaborate specializations of the chorion that protrude from the anterior end of the egg and facilitate embryonic respiration.

The process in which relatively unspecialized cells acquire the specialized features of R1 and R6 photoreceptors. An example of this process is found in Drosophila melanogaster.

The establishment, maintenance and elaboration of the dorsal/ventral axis of the wing disc, a precursor to the adult wing.

The complete process of formation and maturation of an ovum or female gamete from a primordial female germ cell. Examples of this process are found in Mus musculus and Drosophila melanogaster.

The process whose specific outcome is the progression of the lymph gland over time, from its formation to the mature structure. The lymph gland is one of the sites of hemocyte differentiation. It consists of three to six bilaterally paired lobes that are attached to the cardioblasts during larval stages, and it degenerates during pupal stages.

The process in which a cell becomes capable of differentiating autonomously into a neuron regardless of its environment; upon determination, the cell fate cannot be reversed.

The process in which a cell becomes capable of differentiating autonomously into a neuron in an environment that is neutral with respect to the developmental pathway. Upon specification, the cell fate can be reversed.

The process whose specific outcome is the progression of the compound eye over time, from its formation to the mature structure. The compound eye is an organ of sight that contains multiple repeating units, often arranged hexagonally. Each unit has its own lens and photoreceptor cell(s) and can generate either a single pixelated image or multiple images, per eye.

The process whose specific outcome is the progression of the compound eye over time, from its formation to the mature structure. The compound eye is an organ of sight that contains multiple repeating units, often arranged hexagonally. Each unit has its own lens and photoreceptor cell(s) and can generate either a single pixelated image or multiple images, per eye.

The process whose specific outcome is the progression of the compound eye over time, from its formation to the mature structure. The compound eye is an organ of sight that contains multiple repeating units, often arranged hexagonally. Each unit has its own lens and photoreceptor cell(s) and can generate either a single pixelated image or multiple images, per eye.

The process in which the anatomical structures of male genitalia are generated and organized from the genital imaginal disc.

The process in which a relatively unspecialized cell acquires specialized features of a stem cell. A stem cell is a cell that retains the ability to divide and proliferate throughout life to provide progenitor cells that can differentiate into specialized cells.

Any process that modulates the frequency, rate or extent of neurogenesis, the generation of cells in the nervous system.

Any process that stops, prevents, or reduces the frequency, rate or extent of neurogenesis, the generation of cells within the nervous system.

A organ system process carried out by any of the organs or tissues of neurological system.

Any process that modulates the frequency, rate or extent of the assembly of a filopodium, a thin, stiff protrusion extended by the leading edge of a motile cell such as a crawling fibroblast or amoeba, or an axonal growth cone.

A homeostatic process involved in the maintenance of an internal steady state within the germ-line stem-cell niche. This includes control of cellular proliferation and death and control of metabolic function that allows the niche to continue to function. A gem-line stem-cell niche is an anatomical structure that regulates how germ-line stem-cells are used and saves them from depletion.

Formation of a lineage restriction boundary within a developing tissue which does not correspond to some morphological barrier.

A homeostatic process involved in the maintenance of a compartment boundary. A compartment boundary is a lineage restriction boundary within a developing tissue which does not correspond to some morphological barrier.

The morphogenetic process in which an epithelial sheet bends along a linear axis.

The multiplication or reproduction of epithelial cells, resulting in the expansion of a cell population and contributing to the shaping of a Malpighian tubule.

The process in which a relatively unspecialized cell acquires specialized features of a Malpighian tubule tip cell. A Malpighian tubule tip cell is a mitogenic signaling cell that controls the proliferation of its neighboring cells.

Any process in by an organism or tissue maintains a population of neuronal stem cells.

Any process in by an organism or tissue maintains a population of neuronal stem cells.

Any signalling pathway that increases or activates a cell cycle cyclin-dependent protein kinase to modulate the switch from G1 phase to S phase of the mitotic cell cycle.

Any process that modulates the frequency, rate or extent of neuroblast proliferation.

Any process that modulates the frequency, rate or extent of neuroblast proliferation.

Any process that modulates the frequency, rate or extent of stem cell division.

Any process that stops, prevents, or reduces the frequency, rate or extent of cell-cell adhesion mediated by cadherin.

Any cellular process that results in the specification, formation or maintenance of anisotropic intracellular organization or cell growth patterns.

The orderly movement of a neuroblast from one site to another, often during the development of a multicellular organism or multicellular structure. A neuroblast is any cell that will divide and give rise to a neuron.

All of the contents of a cell excluding the plasma membrane and nucleus, but including other subcellular structures.

A membrane-bounded organelle of eukaryotic cells in which chromosomes are housed and replicated. In most cells, the nucleus contains all of the cell's chromosomes except the organellar chromosomes, and is the site of RNA synthesis and processing. In some species, or in specialized cell types, RNA metabolism or DNA replication may be absent.

A membrane-bounded organelle of eukaryotic cells in which chromosomes are housed and replicated. In most cells, the nucleus contains all of the cell's chromosomes except the organellar chromosomes, and is the site of RNA synthesis and processing. In some species, or in specialized cell types, RNA metabolism or DNA replication may be absent.

That part of the nuclear content other than the chromosomes or the nucleolus.

A vacuole to which materials ingested by endocytosis are delivered.

A membrane-bounded organelle that receives incoming material from primary endocytic vesicles that have been generated by clathrin-dependent and clathrin-independent endocytosis; vesicles fuse with the early endosome to deliver cargo for sorting into recycling or degradation pathways.

A prelysosomal endocytic organelle differentiated from early endosomes by lower lumenal pH and different protein composition. Late endosomes are more spherical than early endosomes and are mostly juxtanuclear, being concentrated near the microtubule organizing center.

The volume enclosed by the membranes of the endoplasmic reticulum.

The volume enclosed by the membranes of any cisterna or subcompartment of the Golgi apparatus, including the cis- and trans-Golgi networks.

The part of the cytoplasm that does not contain organelles but which does contain other particulate matter, such as protein complexes.

The membrane surrounding a cell that separates the cell from its external environment. It consists of a phospholipid bilayer and associated proteins.

The membrane surrounding a cell that separates the cell from its external environment. It consists of a phospholipid bilayer and associated proteins.

The component of the plasma membrane consisting of the gene products and protein complexes having at least some part of their peptide sequence embedded in the hydrophobic region of the membrane.

A cell junction at which anchoring proteins (cadherins or integrins) extend through the plasma membrane and are attached to actin filaments.

A cell-cell adherens junction which forms a continuous belt near the apex of epithelial cells.

The external part of the cell wall and/or plasma membrane.

The component of a membrane consisting of the gene products and protein complexes having at least some part of their peptide sequence embedded in the hydrophobic region of the membrane.

A membrane-bounded intracellular vesicle formed by invagination of the plasma membrane around an extracellular substance. Endocytic vesicles fuse with early endosomes to deliver the cargo for further sorting.

A stable assembly of two or more macromolecules, i.e. proteins, nucleic acids, carbohydrates or lipids, in which at least one component is a protein and the constituent parts function together.

The most apical region of the lateral plasma membrane of an invertebrate epithelial cell. The subapical complex lies above the zonula adherens and the septate junction, and is comparable to the position of the tight junction of vertebrate cells.

A DNA-binding transcription factor complex consisting of CSL and mastermind proteins in complex with the cleaved, intracellular domain of Notch. It is required for both repression and activation of Notch target genes.

A DNA-binding transcription factor complex consisting of CSL and mastermind proteins in complex with the cleaved, intracellular domain of Notch. It is required for both repression and activation of Notch target genes.

The region of a polarized cell that forms a tip or is distal to a base. For example, in a polarized epithelial cell, the apical region has an exposed surface and lies opposite to the basal lamina that separates the epithelium from other tissue.