Chapter11 reproductionChapter11 reproduction

Section1 IntroductionSection2 Male reproductionSection3 Female reproduction

Section1 Introduction

Reproduction

The formation of new living entities, which closely resemble to the parent species.

The processes are very complex including production of sperms and ova, sexual intercourse, fertilization, pregnancy, development of fetus and lactation

繁殖季节 常年繁殖：牛、猪、家兔等 季节性繁殖：马、羊、狗等

性成熟和体成熟 性成熟：生殖器官和副性征基本发育完全，具备繁殖能力 , 叫性成熟。 初情期：性成熟的开始阶段 体成熟：动物的生长基本结束 , 并具有成年动物所固有的形态和结构特点 , 称体成熟 .

影响性成熟的因素１、动物的种类和品种 ２、气候因素３、营养因素 ４、群体因素

Section2 Male reproduction

Structure of the male reproductive system

Testis( 睾丸 )

1. Spermatogenesis

2. Endocrine functions

Spermatogenesis

Endocrine functions of testis

1.Androgens:

testosterone

1) Maintenance of spermatogenesis

2) Stimulation of development of genitalia.

3) Development and maintenance of the male secondary sexual characteristics.

4) Maintenance of libido.

5) Effect on metabolism.

Testosterone increases anabolism of protein, especially that in muscle and genitalia, and causes growth of the bones in the thickness, deposition of calcium salts as well enhancement of production of red cells.

2 Inhibin

Inhibin has a strong direct effect on the anterior pituitary gland in inhibiting FSH secretion and a light effect on the hypothalamus in inhibiting GnRH secretion.

These automatic feedback mechanisms can maintain a normal speed of spermatiogenesis, which is required for male reproduction function.

Regulation of Testis Function

Hypothalamic-Pituitary-Testis Axis

(1)GnRH

(2)LHtestosterone

(3)FSH

inhibin

Sperm

HeadNucleus:Acrosome

Midpiece Tail: flagellum

Microtubules:

Section3 Female reproduction

Female Reproductive system

Oogenesis

Ovary

Endocrine functions

Oogenesis

Ovarian Hormones

1.Estrogens

The principle function of estrogen is to cause cellular proliferation and growth of the tissues of the sex organs and other tissues related to production.

Estrogen stimulates the development of sexual organs including ovaries, fallopian tubes, uterus, vagina and the external genitalia.

(1)On sexual organs

(2) On secondary female sexual characteristics.

Estrogen stimulates development of the secondary sex characteristics of female such as feminine figure, soft and smooth skin.

It cause the breast to grow and to show mature appearance.

(3) On metabolism. Estrogen causes a slight increase in

total body protein, which result in growth-promoting effect on the sexual organs, the bones, the breasts and a few other tissues.

Progesterone(1)Effect on uterus. promote secretary changes in the

uterine endometrium, thus preparing the uterus for implantation of the fertilized ovum and providing nutrition for the early dividing ovum.

Progesterone decreases excitability and sensitivity to oxytocin.

It decreases the frequency and intensity of uterine contractions, thereby helping to prevent expulsion of the implanted ovum.

Progesterone(2) Effect on breasts.

Progesterone promotes development of the tubules and alveoli of the breast

(3) Thermogenic effect.

Progesterone causes thermogenic effect and is responsible for the rise in basal body temperature at the time of ovulation.

月经周期中激素、卵巢和子宫内膜的周期性变化

Regulation of ovary function

Hypothalamic-Pituitary-ovary Axis

Events of the Menstrual Cycle

Graafian follicle stimulated

Hypothalamus secretes GnRH

High estrogen levels inhibit FSH secretion, stimulate LH production

Anterior pituitary secretes LH and FSH

LH makes corpus luteum secrete progesterone

Ovaries release estrogen

Decreased LH and FSH levels

Progesterone inhibits LH secretion

Decreased estrogen and progesterone levels stimulate GnRH secretion

LH makes mature follicle burst: ovulation

Corpus luteum atrophies, stops making progesterone

Fol

licu

lar s

tage

Lute

al s

tage

Proliferative phase

Secretory phaseM

enstrual phase

Sexual cycleExtrous cycle

The time intervals from an ovulation to the next. Divide into proestrus, estrus, metestrus and diestrum

Factors effect on estrous cycle:

i) seasonal factors ii) feedstuff: nutritional factoriii) temperature iv) tempt of male to female animal

Fertilization occurs when a few sperm are transported to the ampullae of the fallopian tubes and enter the ovum.

Fertilization

Location of fertilization:ampulla of the fallopian tube

Process of fertilization

2) Sperm and ovum encounter 3) sperm enter ovum: drill through corona radiate pellucid zone enter ovum

4) The formation of malepronucleus and female pronucleus5) Gamete formated

1) sperm capacitationThe process that enables sperm to bind to the ovum

Acrosome reaction:

精子和卵子在输卵管壶腹部相遇。在即将相遇的一瞬间，精子顶体中的酶释放出来以溶解卵子周围的放射冠及透明带

Pregnancy The process in which the fertilized ovum eventually develops into a full term fetus.

(1) egg cleavage

(2) Implantation

(3) formation of placenta( 胎盘 )

Function of placenta:

i)placement of embryo development

ii) Exchange of substance

iii) Endocrine function:PMSG,hCG

受精卵的着床

Parturition