Reproducción

Solo disponible en BuenasTareas
  • Páginas : 9 (2017 palabras )
  • Descarga(s) : 9
  • Publicado : 16 de agosto de 2010
Leer documento completo
Vista previa del texto
Human Reproduction and Development
Human godans
* Primary sexual organs where genes are packaged into gametes
* Male - testes
* Female - ovaries
* Secrete sex hormones
* Regulate secondary sexual traits
Male reproductive system
Sperm cells are able to undergo meiosis (difference from other body cells); they mature in the epididymis. The penis is made up ofSPONGY tissue.

Semen = Sperm + Secretions
* Secretions from epididymis aid sperm maturation
* Seminal vesicle secretes fructose and prostaglandins
* Prostate-gland secretions buffer pH in the acidic vagina
* Bulbourethral gland secretes mucus
Spermatogenesis
* Spermatogonium (2n) divides by mitosis to form primary spermatocyte (2n)
* Meiosis produces haploid spermatids* Spermatids mature to become sperm

Other Testicular Cells
* Sertoli cells
* Line the seminiferous tubules
* Nourish the developing sperm
* Leydig cells
* Lie between the seminiferous tubules
* Secrete testosterone

Male Hormonal Control
Sertoli Cells
Leydig Cells
Anterior Pituitary
Hypothalamus

Hypothalamus

Anterior Pituitary

GnRH
LH
FSHSertoli Cells
Leydig Cells
Testes
Testosterone
Inhibin

Formation and Development of Sperm

Female Reproductive Organs

* Ovary: Oocyte production and maturation, sex hormone production
* Oviduct: Ducts for conducting oocyte from ovary to uterus, fertilization normally occurs here
* Uterus: Chamber in which new individual develops
* Cervix: Secretion of mucus thatenhances sperm movement into uterus and (after fertilization) reduces embryo's risk of bacterial infection
* Vagina: Organ of sexual intercourse; birth canal
* Clitoris: Small organ responsive to sexual stimulation
* Labium Minor: One pair of inner skin folds of external genitals
* Labium Major: One of a pair of outermost fat-padded skin folds of external genitals
* Myometrium: Thickmuscle layers of uterus that stretch enormously during pregnancy
* Endometrium: Inner lining of uterus; site of implantation of blastocyst
Menstrual Cycle
* The fertile period for a human female occurs on a cyclic basis
* Menstrual cycle lasts about 28 days
* Follicular phase and luteal phase
Oocytes Arrested in Meiosis I
* Girl is born with primary oocytes already inovaries
* Each oocyte has entered meiosis I and stopped
* Meiosis resumes, one oocyte at a time, with the first menstrual cycle
Menarche to Menopause
* First menstruation, or menarche, usually occurs between ages 10-16
* Menstrual cycles continue until menopause, in a woman’s late 40s or early 50s
Ovarian Cycle
* Follicle grows and matures
* Ovulation occurs
* Corpusluteum forms
Female Hormonal Control

Hypothalamus

Anterior pituitary

GnRH
LH
FSH

Ovary
Estrogen
Progesterone,
estrogens

follicle growth,
oocyte maturation

Rising estrogen stimulates surge in LH

Corpus luteum
forms

Cycle Overview
* GnRH secretion affects LH and FSH secretion by pituitary
* LH and FSH affect follicle maturation
* Estrogen and progesteronefrom ovary affect uterus
Fertilization
* Sperm penetrates to egg cytoplasm
* Secondary oocyte undergoes meiosis II; forms mature egg
* Egg nucleus and sperm nucleus fuse to form diploid zygote
* A new individual is created
Pregnancy
* Averages 38 weeks from fertilization
* Takes 2 weeks for blastocyst to form
* Weeks 3 to 8 - embryonic period
* Weeks 9 to birth- fetal period
Early Divisions
* Cleavage begins within 24 hours of fertilization
Day #1 Day #2 Day #3 Day#4 (morula)

Day 5 - Blastocyst Forms
* Cell secretions produce a fluid-filled cavity in center of ball of cells
* Layers of blastocyst
* Inner cell mass
*...
tracking img