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Questions and Answers
From which embryonic tissue does the adenohypophysis originate?
What is the origin of the neurohypophysis?
In which week of embryonic development does Rathke's pouch appear?
What is the function of the adrenal glands?
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What is the name of the structure that connects the hypothalamus to the pituitary gland?
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Which of the following is NOT a function of the endocrine system?
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What is the name of the gland that produces hormones for glucose regulation?
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What is the term for the overriding endocrine gland?
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What is the result of the anterior part of Rathke's pouch increasing rapidly during development?
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What develops from the posterior part of Rathke's pouch?
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What is the result of the infundibulum during development?
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What is visible in the adenohypophysis by the 4th month of development?
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What is the result of the neural hypophysis development by the 4th month?
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When are detectable concentrations of GH and ACTH first seen?
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What develops from mesothelial cells between the root of the dorsal mesentery and the developing gonad?
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What type of cells form the fetal cortex?
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What is the result of cells originating from the sympathetic system invading the medial area of the adrenal cortex?
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What is the proportion of the adrenal glands in newborns compared to the size of the kidney?
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What is the process by which the fetal cortex decreases in size after birth?
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What growth factors are involved in the proliferation of the thyroid gland during embryonic development?
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At what point during development does the thyroid gland reach its final position in front of the trachea?
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When does the thyroid gland begin to function and produce colloid-containing follicles?
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What is the structure that connects the thyroid gland to the tongue during its migration?
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What is the fate of the thyroglossal duct?
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In what week of development does the thyroid gland develop a follicular structure?
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Where is the parathyroid gland located?
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What is the main function of the parathyroid gland?
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Which of the following endocrine glands develops from the same embryonic tissue as the thyroid gland?
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What is the relationship between the parathyroid gland and the hypothalamus?
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Which of the following is a characteristic of the parathyroid gland?
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What is the result of the parathyroid gland's dysfunction?
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Which of the following endocrine glands is not directly connected to the parathyroid gland?
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What is the primary function of hormones produced by the parathyroid gland?
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What is the proportion of the adrenal glands in newborns compared to the size of the kidney?
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What happens to the fetal cortex after birth?
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Where does the thyroid gland appear during embryonic development?
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What is the structure that connects the thyroid gland to the tongue during its migration?
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What is the fate of the thyroglossal duct?
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When does the thyroid gland begin to function and produce colloid-containing follicles?
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What is the role of EGF and IGF in thyroid gland development?
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In which week of development does the thyroid gland reach its final position in front of the trachea?
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What is the result of the anterior part of Rathke's pouch increasing rapidly during development?
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What is the origin of the cells that form the pars tuberalis?
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What is the result of the posterior part of Rathke's pouch developing during embryonic development?
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What is the structure that connects the hypothalamus to the pituitary gland?
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What is the result of the infundibulum during development?
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When are detectable concentrations of GH and ACTH first seen?
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What is the origin of the cells that form the adrenal cortex?
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What type of cells form the fetal cortex?
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What is the result of cells originating from the sympathetic system invading the medial area of the adrenal cortex?
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What is the proportion of the adrenal glands in newborns compared to the size of the kidney?
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Study Notes
Endocrine System Development
- 3rd week: Rathke's pouch appears as an evagination of the oral cavity and grows dorsally towards the infundibulum
- 5th week: Rathke's pouch attaches to the neurohypophysis
- By the end of the 2nd month, Rathke's pouch loses its connection with the oral cavity and is in close contact with the infundibulum
Hypophysis Development
- Cells of Rathke's pouch increase rapidly in number and form:
- Anterior part of Rathke's pouch forms the anterior lobe of the hypophysis (pars distalis)
- Small extension of anterior lobe (adenohypophysis) grows along the stalk of the infundibulum and surrounds it → pars tuberalis
- Posterior part of Rathke's pouch develops into pars intermedia (rudimentary)
Infundibulum Development
- The infundibulum gives rise to:
- Median eminence (part of hypothalamus; occasionally included as part of the posterior pituitary gland)
- Neural stalk (=infundibular stem)
- Pars nervosa (=posterior lobe of the hypophysis)
Adenohypophysis Development
- 4th month of development: Adenohypophysis is clearly visible with chromophobes and chromophils, connective tissue stroma, and well-developed capillaries
- Chromophobes are inactive, while chromophils are active and produce hormones such as GH and Prolactin
Neurohypophysis Development
- 4th month of development: Neurohypophysis is finally formed → neuroglia cells differentiate into pituicytes; presence of nerve fibers (axons) that arise from hypothalamus
Hormone Production
- 12th week: Detectable concentrations of GH and ACTH; ACTH stimulates adrenal cortex development
- 20-24 weeks: Peak of release of GH
Suprarenal Glands (Adrenal Glands) Development
- 5th week of development: Mesothelial cells between the root of the dorsal mesentery and the developing gonad begin to proliferate and penetrate the underlying mesenchyme
- Mesothelial cells differentiate into the large acidophilic cells that form the fetal cortex (primitive cortex)
- 7th week: Cells originating in the sympathetic system (neural crest cells) invade the medial area of the already formed fetal cortex, where they form cords and clusters → medulla
- Up to 1st year of life: Intensive fetal cortical atrophy (apart from zona reticularis)
Thyroid Gland Development
- 4th week (24th day): Thyroid gland appears as an epithelial (endoderm) proliferation in the floor of the pharynx at the base of the tongue
- Proliferation occurs due to EGF and IGF
- Subsequently, the thyroid descends in the neck
- During migration, the thyroid is connected to the tongue by a narrow canal, the thyroglossal duct (later disappears)
- 7th week: Thyroid diverticulum reaches the final position in front of the trachea; at this time the small median isthmus and 2 lateral lobes are visible
- 10th week: Follicular structure appears
- End of 3rd month (prenatally): Thyroid gland begins to function; 1st follicles containing colloid become visible
Adrenal Glands
- In newborns, the adrenal glands represent 1/3 of the kidney size.
- Up to 1st year of life, the adrenal glands undergo intensive fetal cortical atrophy, except for the zona reticularis.
- After birth, the fetal cortex regresses rapidly due to apoptosis, except for its outermost layer.
Thyroid Gland
- The thyroid gland appears in the 4th week (24th day) as an epithelial proliferation in the floor of the pharynx at the base of the tongue.
- The thyroid gland descends in the neck, connected to the tongue by the thyroglossal duct, which later disappears.
- In the 7th week, the thyroid gland reaches its final position in front of the trachea, with a visible median isthmus and two lateral lobes.
- The thyroid gland begins to function at the end of the 3rd month, with the first follicles containing colloid becoming visible.
Hypothalamo-Hypophyseal System
- The hypothalamo-hypophyseal system is composed of the hypothalamus and the hypophysis.
- The hypophysis is divided into adenohypophysis (ectodermal) and neurohypophysis (neuroectodermal).
- Rathke's pouch appears in the 3rd week as an evagination of the oral cavity, growing dorsally towards the infundibulum.
- By the end of the 2nd month, Rathke's pouch loses its connection with the oral cavity and is in close contact with the infundibulum.
Pituitary Gland
- The cells of Rathke's pouch increase rapidly and form the anterior lobe of the hypophysis (pars distalis).
- A small extension of the anterior lobe grows along the stalk of the infundibulum and surrounds it, forming the pars tuberalis.
- The posterior part of Rathke's pouch develops into the pars intermedia.
- The infundibulum gives rise to the median eminence, the neural stalk, and the pars nervosa.
- In the 4th month, the adenohypophysis is clearly visible, with chromophobes and chromophils, connective tissue stroma, and well-developed capillaries.
Adrenal Glands (continued)
- The adrenal cortex develops from mesodermal cells, while the adrenal medulla develops from neuroectodermal cells.
- In the 5th week, mesothelial cells between the root of the dorsal mesentery and the developing gonad begin to proliferate and penetrate the underlying mesenchyme.
- These cells differentiate into large acidophilic cells that form the fetal cortex.
- In the 7th week, cells originating in the sympathetic system (neural crest cells) invade the medial area of the already formed fetal cortex, where they form cords and clusters, eventually forming the medulla.
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Description
This quiz covers the development and changes in the adrenal glands of newborns, particularly in the first year of life. It explores the regression of the fetal cortex and the role of zona reticularis.
