Human Reproduction - Gametogenesis Flashcards
What is spermatogenesis
Production of male gametes via mitosis + meiosis
-starts at puberty
-does it at seminiferous tubule (tubule in testes)
-start from peripheral (outer part) of tubule then to inner (lumen)
Spermatogenesis - Mitosis process
Spermatogonium -> 2 primary spermatocytes
-1 spermatocytes will undergo meiosis for gamete
-1 spermatocytes remain the same to become spermatogonium
Spermatogenesis - Meiosis
Primary spermatocytes -> secondary spermatocytes
-1 diploid cell become 2 haploid (Meiosis 1)
-genetically different
-23 chromosomes
Secondary spermatocytes -> Spermatid
-2 haploid to 4 haploid (meiosis)
-genetically different
-23 chromosomes
Spermatogenesis - Differentiation
Spermatids-> Spermatozoa
-cell start to become sperm
-grows mid piece + tail
-happens in inner basement membrane near lumen
-sperm not mobile yet, so release via lumen by peristalsis
Diagram of testes
https://www.histology.leeds.ac.uk/male/assets/testis_diag2.gif
Diagram of spermatogenesis
https://ars.els-cdn.com/content/image/1-s2.0-S187493990900159X-gr4.jpg
Structure of sperm cell
Head:
-streamlined shape: help to penetrate
-acrosome: contain hydrolygic enzyme to break through corona radiata + zona pellucida
-contain DNA easily reach egg if penetrate
Mid piece:
-mitochondria for atp
Tail:
-thin + long to move efficiently
Diagram of sperm cell
https://resource.download.wjec.co.uk/vtc/2020-21/el20-21_1-1/images/eng/4.1_human_reproduction_image_4.png
What is Oogenesis
Mitosis + meiosis of female gametes
-female only get a certain amount of gametes at birth (but more than enough)
-only 1 gamete undergo oogenesis at 1 time
-produce 1 final gamete cells that is large
Oogenesis - mitosis + meiosis
Oogonia
Stem cell undergo mitosis before birth to make a set amount of potential gametes
Oogonia -> primary oocyte
-present at birth
-meiosis 1 stops at prophase 1
Oogenesis - meiosis
Primary oocyte -> secondary oocyte
-Follicle stimulating hormone (FSH) secreted from puberty
-1 gametes start to develop (into 4 haploid cell)
-Meiosis 1 complete, meiosis 2 pause at Metaphase (still conjoined)
-1 big haploid cell with organelles, 3 smaller haploid cell with only chromosome (only 1 egg needed) : polar bodies
Primary follicle -> Secondary follicle -> mature follicle
Oogenesis - ovulation
Secondary oocyte -> ova (egg)
-released from ovary to fallopian tube
-bind with sperm for fertilisation
-meiosis 2 completed upon fertilisation
Oogenesis - process in ovary
Follicular cell - vesicle containing gametes
Follicular fluid - fluid with nutrient to nourish gamete
Primary follicule
-follicular cell start to form around primary oocyte by FSH - meiosis 1
Primary follicule -> secondary follicule
-empty spaces filled with follicular fluid start to form
-primary oocyte become secondary oocyte (4 haploid cell) - meiosis 2
-conjoined polar bodies ejected or dissolved, only polar body + primary oocyte pair left
-secondary oocyte surrounded by smaller follicle cell (corona radiata)
Secondary follicule -> mature follicule
-fluid almost completely surround primary oocyte
Mature follicule -> ovulation
-follicule fuse with ovary wall and secondary oocyte ejected into fallopian tube
Oogenesis - follicle after ovulation
Corpus luteum -> regressed corpus luteum
-empty follicule
-swell up + release progesterone hormone (thicken endometrium lining) + oestrogen (stimulate release of egg * prevent loss of endometrium)
Structure of secondary oocyte
Corona radiata - follicular cell for protection
Zona pellucida - jelly like substance for protection
Haploid polar body - conjoined
Cortical granules - harden wall when sperm touches
Nucleus containing chromosome
Diagram of oogensis in follicular development
https://www.shutterstock.com/shutterstock/photos/116875780/display_1500/stock-photo-oogenesis-and-follicle-development-116875780.jpg
Diagram of secondary oocyte
https://df0b18phdhzpx.cloudfront.net/ckeditor_assets/pictures/1164173/original_01.JPG
