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Reproductive & Development (Meiosis, Spermatogenesis, oogenesis, and…
Reproductive & Development
Male & Female reproductive structures
Male reproductive structures
Reproductive structures
Testes
Produce Sperm & Testosterone
Scrotum
Controls temperature of testes
Seminiferous Tubules
Where sperm is made
Interstitial cells
Testosterone production
Vas deferens
Carries Sperm through ejaculatory duct
Ejaculatory duct
Takes sperm through prostate
Penis
Delivers sperm to vigana
Urethra
Carries semen & urine to outside the body
Prostate gland
Raises semen PH
Seminal Vesicle
Provides fructose for nourishment
Cowper's Gland
Adds lubrication
Copora cavernosa & Corpus spongiosum
Fills with blood to cause erection
Epididymis
Coiled tubule that stores sperm
Female reproductive structures
Reproductive structures
Ovary
Production + Maturation of an Oocyte, Hormone production
Uterine Tube
Carries zygote to uterus, site of fertilization
Uterus
Site of implantation, protects and nourishes a developing human
Vigana
Receives Sperm + is the birth canal
Clitoris
Sexual Stimulation
Graafian Follicles
Mature Follicles
Meiosis, Spermatogenesis, oogenesis, and Menstrual cycle
Meiosis
Meiosis 1
Prophase 1- Homologous pairs of chromosome are separated after synapsis and crossing over occurs
Metaphase 1- Homologous replicated chromosomes line up obove and below the equator of the cell , forming a double line of chromosomes
Anaphase 1 - Maternal and paternal pairs of replicated chromosomes are separated and pulled in opposite ends of the cell, a process called reduction division. siter chromatids remain attached
Telophase and cytokinesis 1- the opposite of prophase 1 and two cells are produced each containing 23 replicated chromosomes only, still composed of sister chromatids
Meiosis 2
Prophase 2 - Nuclear envelope breaks down and replicated chromosomes cluster together. there is no crossing over
Metaphase 2 - Spindle fibers extend from the centrioles to each chromatid in each chromosome and align the replicated chromosomes along the equator of the cell
Anaphase 2 - Sister chromatids of each replicated chromosome are pulled apart at the centromere . sister chromatids now called single chromosomes
Telophase and cytokinesis 2 - Nuclear division finishes the nuclear envelope re form. Four new daughter cells are produced each containing 23 single chromosomes only
Oogenesis
Before birth
Oogenia are diploid cells containing 23 pairs of chromosomes that are the orgin of the oocytes. Mitotic divisions of oogonia produce primary oocytes , which are diploid cells.
Primary oocytes start the process of meiosis but are arrested in prophase 1
Follicle development - primordial follicle
Childhood
Ovary is inactive . it houses primordial follicles . some atresia of primordial follicle occurs
Meiosis 1 arrested
Monthly , from puberty to menopause
Up to approximately 20 primordial follicles mature into primary follicles every month . some primary follicles mature into secondary follicles . primary follicles that do not mature undergo atresia
Typically only one secondary follicle matures into a mature follicle , where the primary oocyte completes the first meiotic division to produce a polar body and secondary oocyte , The secondary oocyte is a haploid cell that is arrested in the second meiotic metaphase
If the secondary oocyte is fertilized it completes the second meiotic division and becomes an ovum , if the secondary oocyte is not fertilized , it degenerates .
Spermatogenesis
Germ cells that are the orgin of the sperm are diploid cell containing 46 chromosomes , or 23 pairs called spermatogonia . Mitotic divisions of these cells produce a new germ cell and a committed cell, The committed cell is a primary Spermatocyte
Meiosis 1 begins in the diploid primary spermatocytes . the haploid cells containing 23 chromosomes only produced during meiosis 1 are called secondary spermatocytes
Meiosis 2 originates with the secondary spermatocytes and produces spermatids.
The process of spermiogenesis begins with spermatids and results in morphologic changes needed to form sperm that will be motile
Menstrual cycle
Menstrual Phase
Occurs during 1-5 days in the cycle. This phase is marked by sloughing of the functional layer of the endpmetrium and lasts through the period of menstrual bleeding
proliferative phase
follows , spanning approximately 6-14 days . this is the initial development of the new functional layer of the endometrium overlaps the time of follicle growth and estrogen secretion by the ovary
Secretory phase
occurs 15- 28 days. During secretory increased vascularization and development of the uterine glands occcurs primarly in response to progesterone secretion from the corpus luteum
Hormones
Female
GnRH
Hypothalamus
stimulates anterior pituitary to produce and secrete FSH AND LH
FSH
Anterior pituitary
Stimulates development and maturation of ovarian follicle
LH
Anterior pituitary
Stimulates ovulation when there is a peak in LH
Estrogen
Ovarian follicles before ovulation , corpus luteum after ovulation , or placenta during pregnancy
Initiates and maintains growth of the functional layer of the endometrium
Progesterone
corpus luteum or placenta during pregnancy
Primary hormone for functional layer growth after ovulation; causes increase in blood vessel distribution , uterine gland size, and nutrient production
Inhibin
Ovarian follicles
Inhibits FSH secretion so as to prevent excessive follicular development
Male
GnRH
secreted by the hypothalamus stimulates the anterior pituitary to secrete FSH AND LH
LH
stimulates interstitial cells to secrete testosterone
FSH
stimulates sustenticular cells to secrete ABP, which helps keep testosterone levels high on the testes
Testosterone
stimulates spermatogenesis but inhibits GnRH secretion and reduces the anterior pituitary's sensitivity to GnRH
Rising sperm count levels cause sustentacular cells to secrete inhibin , which which further inhibits FSH secretion
Embryonic and Fetal Development
Embryonic
week 3 is considered an embryo
Primitive streak appears, gastrulation occurs three primitive layers form.
Notochord developes and Neurulation begins with neural fold and neural groove
week 4
heart is formed and its the first organ to function
somites are semi developed but still are cartilage
Liver also starts to develop
Week 5
same as week 4 but the embryo develops an optic vesicle and Arm and leg buds
Week 6 to end of 8 or beginning of 9
All internal organs complete , some functioning
Extremities develop from limb buds
Cartilage skeleton and muscles complete
placenta and umbilical cord function, Facial features and ears nearly complete , and embryo assumes a human appearance
Layers
endoderm
develops into the digestive and its derivatives
mesoderm
This will form the circulatory system, excretory system , most reproductive and skeletal and muscles
Ectoderm
It develops into the nervous system , sense organs , skin and skin derivatives
Fetal Development
9- 12 weeks
Primary ossification centers appear in most bones, reproductive organs begin to develop
Coordination between nerves and muscles for movement of limbs occurs
Brain enlarges , body enlarges , epidermis of the skin become more fully developed , permanent kidneys develop , plate roof of mouth developes
weeks 13- 16
Body grows rapidly , ossification in the skeleton continues
Limbs become more proportionate in length to the body , and brain and skull continue to enlarge
week 17-20
Muscle movements become stronger and more frequent , lunugo covers skin
limbs near final proportions , brain and skull continue to enlarge
weeks 21-38-
body gains major amount of weight , subcutaneouse fat is deposited , eyebrows and eyelashes appear
eyelids open , testis decent into scronum month 9, and blood cells form in marrow only