Gametogenesis, spermatogenesis, spermiogenesis Flashcards
What is Fertilization?
Male and female gametes fuse giving rise to the formation of the zygote…
What is Zone Pellucida (ZP)?
Specialized extracellular matrix (ECM) which is produced by the oocyte and follicular granulosa cells
4 main glycoproteins of Zona Pellucida
ZP1, ZP2, ZP3, ZP4
Functions of Zona Pellucida in general
protection, transport, sperm binding, prevention of polyspermy, support of blastocyst development, prevention of early implantation
Function of Zona Pellucida (specifically)
required for structural integrity of the matrix, minimize precocious hatching
Function of ZP1, ZP3 and ZP4
binds to the capacitated human spermatozoa
→ induce acrospmal reaction
Function of ZP2
Sperm recognition receptor
Important role in defence against polyspermy.
How can play an important role in defense against polyspermy?
It is cleaved by ovastacin released from cortical granules after fertilization and other sperm can not bind to the oocyte
What is Gametogenesis?
the conversion of germ cells into male and female gametes
Primordial germ cells (PGCs) give rise to ___ (2 type of cells)
Sperm cells and Oocytes
What happen during prenatal events of Gametogenesis?
-
Primordial germ cells develop from epiblast during the second week
- → appear in the wall of the yolk sac at the end of the 3rd week of development
-
Germ cells migrate from the yolk sac toward the developing gonads (primitive sex glands)
- → arrive at the end of the 4 th or the beginning of the 5 th week
What is Spermatogenesis?
the sequence of events by which spermatogonia are transformed into mature gametes: sperm (spermatozoa).
3 events occur during spermatogenesis
- Spermacytogenesis
- Meiosis
- Spermio(histo)genesis
What is Spermatocytogenesis?
Asymmetric division of spermatogonia.
(Some of them remain „stem cell”, others start the differentiation process.)
What is Spermio(histo)genesis?
spermatids are transformed to sperm that can fertilize eggs
3 main events of spermatogenesis?
- Spermatocytogenesis : asymmetric division of spermatogonia. Some of them remain „stem cell”, others start the differentiation process.
- Meiosis: meiotic division of spermatocytes (I and II)
- Spermio (histo)genesis: spermatids are transformed to sperm that can fertilize eggs
How can spermatogonia become spermatids?
Spermatogonia
→ mitosis, growth
→ primer spermatocytes
→ first meiotic division
→ secunder spermatocytes
→ second meiotic division
→ spermatids
4 main events of Spermiohistogenesis
(transformation of spermatids into spermatozoa)
(a) Formation of acrosome cap (lysosome-hydrolytic enzymes foracrosomal reaction of fertilization)
(b) Condensation and elongation of the nucleus
(c) Development of flagellum (formation of neck, middle piece and tail)
(d) Shedding of most of the cytoplasm
Where are male germ cells?
in the sex cords of the testis
Which cells are supporting male germ cells (PGCs)? Where are they derived from?
The supporting cells are derived from the surface epithelium of the testis and become Sustentacular/Sertoli Cells
