Fertilization & Implantation

Topics for today:

• Structure of testes • Action of testosterone • • Steps of • Fertilization • Implantation

Functional anatomy of testes

Site of storage Site of androgen synthesis

Sperm passageway Interstitial tissue (between tubules)

Site of spermatogenesis

1 Micro anatomy of testes

Interstitial tissue, site of synthesis of testosterone OH

O testosterone

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Hormonal effects of androgens (general effects)

• produce a general ‘anabolic’ effect • stimulates protein synthesis (muscle tissue) and male body configuration • stimulates bone elongation and relatively quick closure of the epiphyseal plates • promotes male pattern of hair growth

Hormonal effects of androgens (reproductive system effects)

• promotes descent of testes into scrotum

2 Hormonal effects of androgens (reproductive system effects)

Stimulates growth of secondary sex glands

Stimulates function of these glands

secretes fructose, nutrient for spermatozoa

- secretes HCO3 rich fluid; neutralizes acid of vaginal epithelium

Hormonal effects of androgens (reproductive system effects)

• stimulates growth of ductus deferens and external genitalia

Seminiferous tubule gametogenisis

seminiferous tubule

3 spermatogonium

Meiotic stages of hypertrophy

spermatogenesis primary I

secondary meiosis II

spermatids

transformation spermatozoa

Structure and Biochemistry of Spermatozoa

Secretes hyaluronidase that can degrade zona pellucida

Meiotic stages of oogonium Oogenesis (2n) hypertrophy primary (2n)

Meiosis I

secondary 1st polar oocyte body (1n)

Meiosis II

2nd polar Ovum body (1n)

4 comparison oogonium spermatogonium (2n) hypertrophy (2n)

primary oocyte primary (2n) spermatocyte (2n) meiosis I secondary secondary spermatocytes (1n) 1st polar oocyte body (1n) meiosis II spermatids (1n)

2nd polar ovum transformation body (1n) spermatozoa (1n)

Fertilization

(diploid)

Implantation morula

fertilization

blastula

endometrium day 7

Chorion formation & release of chorionic gonadotropin

5 Early Stages

ovum fertilization Zygote cleavage morula blastulation blastula 0 d 3 d 5 d spermatozoan stage at implantation

Topic for Tuesday:

Embryo Development

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