Flashcards
Spermatogonia
Undifferentiated germ cell (male) which undergoes mitosis
Spermatocytes
Celltype differentiated from spermatogonia. Primary spermatocytes (2N) undergo meiosis I where two secondary spermatocytes (N) are formed
Spermatids
Are formed when secondary spermatocytes (N) undergo meiosis II. When formed, early round spermatids must undergo further maturational events to develop into spermatozoa, a process termed spermiogenesis. A residual body is left after the spermazoa are formed.
Oogonium
These are produced during embryo development through mitotic division. Before birth, these will differentiate further
Primary oocyte
Oogonia will either degenerate or further differentiate into primary oocytes through asymmetric division. Asymmetric division is a process of mitosis in which one oogonium divides unequally to produce one daughter cell that will eventually become an oocyte through the process of oogenesis, and one daughter cell that is an identical oogonium to the parent cell. This occurs during the 15th week to the 7th month of embryonic development. Primary oocytes will undergo oogenesis in which they enter meiosis. However, primary oocytes are arrested in prophase 1 of the first meiosis and remain in that arrested stage until puberty begins in the female adult.
Four types of cell communication
- Endocrine signaling
- Paracrine signaling
- Autocrine signaling
- Signaling by plasma-membrane-attached proteins = juxtacrine signaling
Components of ECM
- Glycosaminoglycans (GAGs)
- Proteoglycans
- Collagens
- Fibers, e.g., elastin
- Glycoproteins, e.g., fibronectins and laminins
Types of intercellular connections
- Tight junction
- Adherens junction
- Desmosome
- Gap junction
- Hemidesmosome
Function of tight junction
Seals neighboring cells together in an epithelial sheet to prevent leakage of molecules between them
Function adherens junction
Joins an actin bundle in one cell to a similar bundle in a neighboring cell
Function desmosome
Joins the intermediate filaments in one cell to those in a neighbor
Function gap junction
Allows the passage of small water-soluble ions and molecules
Function hemidesmosome
Anchors intermediate filaments in a cell to the basal lamina
Examples of cell adhesion molecules
Integrins, selectins, cadherins, Ig superfamily
Cleavage (embryogenesis)
Cleavage is a process that occurs with a unique nature in mammals. During cleavage, the zygote undergoes multiple rapid cell divisions, without any significant overall growth. This produces a cluster of cells the same size as the original zygote. In other words, the number of cells and nuclear mass increases, while the cytoplasmic mass does not.
The different cells derived from cleavage are called blastomers and they form a compact mass called the morula. Cleavage ends with the formation of the blastula (blastocyst in mammals).
In mammals, rotational cleavage occurs, meaning that the blastomers divide around different axes. There’s also an asynchrony of early cell division, meaning that cells divide with different speed.
Compaction (embryogenesis)
A key event prior to morula formation is “compaction”, where the 8 cell embryo undergoes changes in cell morphology and cell-cell adhesion that initiates the formation of this solid ball of cells.
Gastrulation
The process where the blastula (blastocyst in mammals) is reorganized from a single-layered hollow sphere of cells into a multilayered structure known as the gastrula. In mammals, the gastrula consists of three layers - the ectoderm, mesoderm, and endoderm
Definition cell culture
Cell culture is the process by which cells are grown under controlled conditions, generally outside their natural environment.
Primary cells
= mature cells
Precursor cells
= immature cells of a specific type
