Animal Biology: Cell Division, Histology, and Tissue Types

Vocabulary flashcards covering cellular division, gametogenesis, histology staining techniques, epithelial classifications, connective tissues, muscle types, and neural cell structures.

Homologous Chromosomes

Pairs of maternal and paternal chromosomes that code for the same genetic traits.

Mitosis

The process of cell division that creates two identical diploid daughter cells for growth and repair or replacement.

Interphase

The phase between cell divisions where chromosomes exist as diffuse chromatin, DNA is replicated identically, new organelles form, and energy reserves are built up.

Prophase

The stage of mitosis where replicated chromatin condenses, centrioles migrate to the poles, spindle formation commences, and the nuclear membrane breaks down.

Metaphase

The mitotic phase where chromosomes migrate to the cell equator, attach to spindles, and sister chromatids orient toward opposite poles.

Anaphase

The mitotic phase where sister chromatids are pulled toward opposite poles by pole-to-pole and pole-to-centromere spindles using mitochondrial energy.

Telophase

The final stage of mitosis where chromatids reach the poles, the spindle apparatus breaks down, the nuclear membrane reforms, chromatids unwind, and cytokinesis splits the cell.

Meiosis

A form of cell division comprising two successive divisions that produces four non-identical, haploid gametes.

Bivalent

A pair of associated homologous chromosomes that become intimately entangled during prophase I of meiosis.

Chiasmata

The points of contact where homologous chromosomes remain joined and where genetic exchange occurs during crossing over in prophase I.

Spermatogonia

Diploid, undifferentiated stem cells situated under the capsule of the seminiferous tubules that undergo mitosis to begin spermatogenesis.

Oogonium

A germ cell in the outermost layers of the ovaries that undergoes mitosis before birth to generate primary oocytes.

Histology

The study of the structure of tissues at the cellular level.

Histopathology

The study of diseases of the tissues through the microscopic examination of tissues and/or cells.

Haematoxylin

A basic histological dye that binds to acidic cellular components, staining the nucleus, ribosomes, and basophilic structures deep blue or purple.

Eosin

An acidic histological dye that binds to basic cytoplasmic components, staining the cytoplasm, cell boundaries, and extracellular fibres pink or red.

PAS Alcian Blue

A special dual-staining technique using Alcian Blue and Schiff's reagent to distinguish between acidic mucopolysaccharides (stained blue) and neutral mucins or glycogen (stained magenta/purple).

Apical Surface

The distinct epithelial cell surface that faces the exterior body surface, an internal cavity, or the lumen of an organ.

Basal Surface

The surface of an epithelial cell attached to a basement membrane, which anchors the epithelium to underlying connective tissue.

Exocrine Glands

Glands with ducts, such as salivary or sweat glands, which can be unicellular (like goblet cells) or multicellular.

Endocrine Glands

Ductless glands that secrete substances directly into circulation or the pituitary gland, such as the thyroid and pituitary glands.

Microvilli

Epithelial surface specialisations that increase the surface area of a cell without significantly increasing its overall size.

Cilia

Hair-like surface projections that assist in the movement of material over the epithelial surface.

Fibroblasts

The most abundant connective tissue cells; they synthesise extracellular matrix components, secrete collagen and elastin, and play key roles in wound healing.

Adipocyte

A specialised connective tissue cell that stores lipids in large cytoplasmic droplets, displacing the nucleus to the periphery and creating a signet ring appearance.

Smooth Muscle

Involuntary, non-striated muscle composed of spindle-shaped cells with a single central nucleus that controls hollow organ and vessel diameter.

Skeletal Muscle

Striated, multinucleated voluntary muscle arranged in sarcomeres that accounts for $30-40\%$ of total body mass and attaches to bones via tendons.

Cardiac Muscle

Involuntary, fatigue-resistant striated muscle that contracts rhythmically via an actin-myosin sliding filament mechanism to pump blood.

Perikaryon

The cell body of a neuron, mainly found in the central nervous system or peripheral ganglia.

Axon

A single nerve fibre ranging from $0.2\,\mu\text{m}$ to $20\,\mu\text{m}$ in diameter and up to around $1\,\text{m}$ in length that transmits electrical impulses to the distal end.