Mnu Histology

Front 1

Where is the pituitary gland located?

What are its relations?

Back 1

Sella turcica of the sphenoid bone.

Relations:

Lateral: cavernous sinus
Anterior: sphenoid air sinus and nasopharynx
Posterior: dorsum sellae.
Above: dura matter of diaphragma sella, separating it from optic chiasm. Infundibulum passes through the diaphrgma to attach it to the hypothalamus.

Front 2

The pituitary is divided into the ANTERIOR LOBE (adenohypophysis) and the POSTERIOR lobe (neurohypophysis).

What are the parts of the anterior lobe?

Parts of the posterior lobe?

Back 2

Anterior lobe: main part is the pars distalis. Pars tuberalis forms a collar around the stem, and the pars intermedia is squished in the middle.

Posterior: Pars nervosa: connected to a part of the hypothalamus, and the infundibulum, which connects the nervosa to the stem and the median eminence of the hypothalamus.

Note: reminants of Rathke's pouch are located between the pars intermedia and the pars distalis.

Front 3

How does the pituitary gland develop?

Back 3

From 2 sources: the posterior lobe develops as a downgrowth of the developing nervous system (neural tube) and the anterior lobe is an upgrowth of Rathke's pouch from the roof of the mouth. The association with the hypothalamus is retained via the infundibulum, the association with the mouth is lost.

Front 4

Outline the structure of the neurohypophysis.

What are the 2 big groups of neurons?

Back 4

Composed of unmyelinated neurons coming from neurons in the hypothalamus.

2 groups: the paraventricular nucleus, and the supraoptic nucleus.

These send axons through the infundibulum into the pars nervosa and terminate in association with blood vessels. Hormones are channeled downward and stored in the axon terminal for release.

Front 5

What does the paraventricular nucleus synthesize? What is its function?

Back 5

Synthesizes oxytocin. This acts on smooth muscle in the uterus to promote contraction, and induces milk release (not production!) in the myoepithelial cells of the breast to constrict to help eject milk.

Front 6

What does the supraoptic nucleus primarily produce? Function?

Back 6

Vasopressin (ADH).

This will act on the kidney to increase uptake of H2O from the tubules and decrease urine output.

Front 7

The anterior lobe has 2 main cell types. What are they and what do they do?

Back 7

CHROMOBHOBES: avoid colour, light staining, blue cells. These are a stem cell population to replenish other cells that have released their secretions.

CHROMOPHILS: further divided into 2 types....Acodiophils (eisonophillic, darker staining and pink) and Basophils (blue) which contain and release main secretions.

Front 8

There are 2 types of acidophils. What are they and what do they do?

Back 8

Acidophils: divided into:

Somatorophic cells: release somatotrophin (GH), act on bone growth via somatomedins synthesized in the liver. Stimulated by GHRH (SRH) and inhibited by somatostatin (@ hypo. level).

Mammotrophic cells: secrete prolactin - milk production. These promote milk synthesis. Stimulated by Prolactin-releasing hormone (PRH) and inhibited by Prolactin-inhibiting hormone (PIH)

Front 9

There are 3 types of basophils. What are they and what do they do?

Back 9

Gonadotrophic cell: produce FSH and LH. FSH promotes ovarian follicle development and estrogen secretion in female, stimulates spermatogenesis in male. LH promotes ovarian follicle maturation and progesterone secretion. Stimulates Leydig cells in male for androgen secretion. Stimulated by GnRH.

Thyrotropic cell - produces TSH. Stimulates thyroid hormone synthesis, storage, release. Stimulated by TRH.

Corticotropic cell: produces ACTH. Stimulates secretion of adrenal cortex hormones. Stimulated by CRH (corticotropin releasing hormone).

Front 10

What controls the activity of cells in the adenohypophysis?

Back 10

Controlled by factors released by hypothalamus. There is no direct tissue connection between hyopthalamus and anterior pit, and these must distribute to it through the hypophyseal portal system.

Front 11

What is a portal system?

Back 11

Portal system: arrangement where blood is collected from one set of capillaries and passes through another set of capillaries before returning to general systemic circulation. E.g. hepatic portal system (stomach and intestines to liver), renal portal system (glomerulus to peritubular plexus).

Front 12

How does the hypothalamic portal system work?

Back 12

Axon terminals of neruons in the hypothalamus release factors taken up by capillaries (primary capillary plexus) in the median eminence and infundibulum.

Veins draining the primary plexus carry these to the capillary plexus in the adenohypophysis (secondary capillary plexus) and chromophil activity is increased.

Hormones released from chromophils and enter the vessels of the secondary plexus. BLood from secondary plexus enters general circulation to target cells.

Front 13

Thyroid time!

Where is the thyroid derived from?
Describe the structure.

Back 13

Derived from endoderm in the floor of the embryonic pharynx, via thyroglossal duct.

Structure: connective tissue capsule with septae. Composed of spherical follicles seperated by loose connective tissue and plexuses of fenestrated capillaries.

Front 14

What are follicles lined with?

What do follicles do?

Back 14

Lined with simple squamous to simple columnar epithelium depending on activity (tall and small = active).

Thyroglobulin is synthesized by FOLLICULAR cells and secreated into follicle. Iodine is removed from blood, oxidized, and released into follicle, where it binds with tyrosine residues on thyroglobulin. TSH stimulation makes follicular cells phagocytose colloid. Vacuoles fuse with lysosomes, and T3 and T4 are released into the cell tytoplasm, where they travel to the fenestrated capillaries for release.

Front 15

What do thyroid hormones do?

Back 15

Increase basal metabolic rate and promote growth and development.

Front 16

What is Grave's Dx?

Back 16

Thyrotoxicosis. Antibodies made to TSH receptor, stimulating activity and phagocytosing ++ colloid. Follicles begin to collapse inward. Big eyes, increased metabolism.

Front 17

What are parafollicular cells? What do they produce? What does it do?

Back 17

Lightly staining clear cells, producing calcitonin to lower serum calcium by suppressing osteoclast activity.

Front 18

Describe the structure of the parathyroid gland.

What are the 2 main cell types? What do they do?

Back 18

Connective tissue capsule dividing it into lobes.

2 main cell types: oxyphils and chief cells.

Oxyphils-?
Chief cells: produce parathyroid hormone to stimulate osteoclasts to raise serum calcium by increasing their number and activity.

Front 19

What are the actions of parathyroid hormone on: bone? GI? Kidney?

Back 19

Bone: promotes resorption.
GI: stimulates Ca absorption.
Kidney: decreases Ca secretion, promotes calcitrol synthesis (a form of vitamin D increasing Ca uptake in the gut).

Front 20

Describe the structure of the testicle.

Back 20

Surrounded by a dense, fibrous connective tissue capsule called the tunica albuginea. This sends septae into the gland and divides it into lobules. Each lobule contains 1-4 seminiferous tubules.

Surrounding the tunica albuginea is the visceral tunical vaginalis, followed by the parietal tunical vaginalis.

Front 21

What 2 structures are contained external to the spermatogenic cells?

What does the lining of the seminiferous tubercle consist of?

Back 21

1. lamina propriia.
2. myloid cells - long oval nuclei with contractile properties.

Lining consists of a modified stratified epithelium that is uncomplicated before puberty and changes at puberty.

Front 22

Outline the process of spermatogenesis.

Back 22

Starts at the basement membrane where there are Type A spermatogonia.

There are 2 types of Type A spermatogonia: a dark staining, slow, quiet type which is a progenitor cell, and a light staining, pale type in a more rapid cell cycle. This is also a progenitor cell, but can give rise to type B cells.

Type B cells are still on the basement membrane, but move off it. Once this occurs, they are not progenitor cells. Moving off the basement membrane is a signal for meiosis.

Primary spermatocytes undergo meiosis 1. Secondary spermatocytes undergo meiosis 2 to become spermatids.

Spermatids undergo rearrangement to become spermatozoa. This is called spermiogenesis, and involves casting off excess cytoplasm to leave behind a residual body.

Key: in contact with basement membrane = spermatogonia, off membrane = spermatocytes.

Front 23

Outline the 7 functions of sertoli cells.

Back 23

1. Nourish and support spermatogona cells.
2. Control progression thorugh mieosis.
3. Produce testicular fluid in seminiferous tubule.
4. Produce ABP (androgen-binding protein)
5. Produce inhibin to negatively feedback on FSH
6. Phagoyctose resuidual bodies.
7. Create a blood testis barrier via tight junctions.

Front 24

What are the contents of the interstitial connective tissue in the testicle?

Back 24

1. Leydig cells
2. Fenestrated capillary network in interstitial connective tissue.

Front 25

Describe the structure of the epididymis.

Back 25

A compartment on the posterior surface of the testicle with a connective tissue capsule and tubules packed in, contains some smooth muscle.

Front 26

Describe the structure and function of the tubules.

Back 26

Tubules are lined with pseudostratified columnar epithelia. The cells have long microvilli known as stercocilia. There are 2 types of cells: the principle cells with oval nuclei, and the basal cells (progenitor population) with round nuclei.

Function: sperm storage and maturation - swimming lessons!

Front 27

Outline the structure of the vas deferens.

Back 27

Tube with several layers to the wall, most of which is smooth muscle.

Innermost: mucosa layer of pseudostratified columnar epithelia, note this is one of the only places where this is found.

Middle: smooth muscle arranged with an inner longitudinal layer, middle circular layer, and outer longitudinal layer.

Outer adventitia or connective tissue.

Front 28

Describe the structure of the seminal vesicles.

Back 28

These are coiled bags connecting the vas deferens to the prostate gland. These are composed of pseudostratified columnar epithelium on the inner layer with mucosa, then progress to a muscularis layer with an inner ciruclar orientation and an outer longitudinal layer, followed by adventita.

Front 29

Describe the structure of the prostate gland.

Name the classifications of glands.

Back 29

Fibroelastic capsule with dense connective tissue with smooth muscle fibers scattered throughout. Long, branching glands are scattered within.

Glands: mucosal (around urethra), submocusal, and the main prostatic glands lying around the periphery with long ducts (malignant hyperplasia affects these).

Front 30

What are the 3 layers of the ovary?

Back 30

Tunica albugenia (connective tissue capsule).
Germinal epithelium (peritonal covering), made of simple cuboidal epithelium (normal peritoneum is simple sqamous epithelium!).
Cortex - where the follicles are.

Front 31

What phase is a primary oocyte arrested in?

When do secondary oocytes appear?

Back 31

Meiosis I.

Appear before ovulation when first meiotic division completes.

Front 32

What is a primordial follicle?

How does a primary follicle differ?

Back 32

Single layer of flattened follicular (granulosa) cells attached to each other by gap junctions.

Primary: folicuar cells become cuboidal in shape and form a multi-layer envelope.

Front 33

What is the zona pellucida?

How are follicular cells connected to each other?

Back 33

Lies between the primary oocyte and inner layer of follicular cells. Separated from theca by a basement membrane.

Gap junctions.

Front 34

What are the 2 layers the theca gives rise to?

Back 34

Theca interna: steroid-producing cells which secrete androgens taken up by follicular cell and converted to estrogen.

Theca extrena: outer fibrous layer.

Front 35

How can you distinguish a secondary follicle from a primary one?

Back 35

Fluid-filled spaces among the follicular cells.

Front 36

Corpus Luteum:
Composed of cells from?

Follicular (granulosa) cells enlarge and secrete ______________.
Cells of the theca interna secrete _______.

Back 36

Graffian follicles remaining after ovulation....follicular cells and theca.

Estrogen and progesterone.
Progesterone

Front 37

What are the 3 layers of the uterus?

Back 37

Serosa-connective tissue and peritoneum
Myometrium-smooth muscle.
Endometrium (mucosa): simple columnar epithelium forming tubular glands penetrating the lamina propria.

Front 38

What are the 2 layers of the endometrium?

Glands are _____-staining and ______ during the follicular (proliferative) phase. Glands are ______-staining and ______ in the luteal (secretory) phase due to the accumulation of ________.

Back 38

Stratum functionalis - lost at menstruation.
Stratum basalis - regenerates stratum functionalis.

Glands are DARK-staining and STRAIGHT during the follicular (proliferative) phase. Glands are PALE-staining and TWISTED in the luteal (secretory) phase due to the accumulation of GLYCOGEN.

Front 39

The cervix has a ______ _______ epithelium supported by a thick fibrous connective tissue.

How does the epithelium change a the external os?

Back 39

SIMPLE COLUMNAR.

Changes to stratified squamous non-keratinized.

Front 40

What surrounds the ostium of the uterine tube?

What are the parts of the uterine tube?

Back 40

Fimbria.

Infundibulum, ampulla, isthmus, intramural.

Front 41

What are the 3 layers of the uterine tube, and what type of epitheium is each made of (where applicable)?

Back 41

Mucosa - simple columnar epithelium cells which rest on a connective tissue lamina propria. There are cilated epithelial cells and non-ciliated secretory cells.

Muscularis: with inner circular layers and outer longitudinal.

Serosa - continuous with the broad ligament.

Front 42

Describe the structure of the breast.

Back 42

-15-20 lobes with a duct opening onto the nipple. Each lobe is a compound gland made up of lobules supported by a cellular loose connective tissue, seperated from adjacent lobules by a less cellular, more fibrous connective tissue.

Front 43

What is the non-lactating breast made of?

What happens to the breast during pregnancy?

Back 43

Connective tissue and a rudimentary duct system. Accumulation of adiopcytes increases breast size.

Pregnancy: duct system further develops and secretory alveoli bud from the smallest branches of the duct system. Intralobar connective tissue is reduced to thin septae.