General organ structure plan
Any parenchymal organ consists of two interrelated parts: the parenchyma and the stroma.
- Connective tissue framework: The organ is covered externally by a dense capsule, from which connective tissue septa—trabeculae—extend inward.
- Parenchyma: Located in the intertrabecular space and performs specific functions. In organs of the immune system, it is divided into zones: the peripheral dark cortex, the intermediate paracortical zone, and the central medulla.
- Clusters of immune system cells and lymphatic sinuses for lymph transport are concentrated within the parenchyma.
Features of the parathyroid gland stroma
The stromal apparatus of the parathyroid gland has unique features that distinguish it from other endocrine organs.
- Externally, the gland is covered by a connective tissue capsule.
- Thin layers of loose fibrous connective tissue, penetrated by a dense network of blood vessels, extend into the organ.
- An important histological feature of the stroma is the presence of adipocytes (fat cells).
- The parenchyma is based on epithelial cords and compact cell clusters.
Renal stroma and capsules
The kidney is surrounded by three protective layers that ensure its fixation and normal functioning:
- The outermost layer is the connective tissue fascia.
- Beneath it lies the adipose capsule (renal fat), consisting of adipose tissue.
- Immediately adjacent to the parenchyma is a thin plate—the fibrous capsule (capsula fibrosa).
An interesting feature of the fibrous capsule is the presence of smooth muscle elements (myocytes). Their contraction maintains intrarenal pressure for plasma filtration and facilitates urine excretion.
Vascularization and stroma of the corpus luteum
In endocrine structures, such as the corpus luteum of the ovary, the stroma acts not only as a framework but also as a powerful nutritive apparatus.
- Thin layers of connective tissue are located between the large luteal cells of the parenchyma.
- Abundant vascularization is characteristic: a dense network of capillaries and large vessels permeates the entire tissue of the organ.
- Externally, the entire structure is reliably surrounded by a protective layer of fibrous connective tissue.
Capsule outside, trabeculae inside — the organ's framework is secured!
Class and exam questions
What tissue are the organ capsule and trabeculae made of?
The connective tissue framework (capsule and trabeculae) is formed by dense fibrous connective tissue.
What unique elements are present in the fibrous capsule of the kidney?
In addition to connective tissue, it contains smooth muscle elements (myocytes) that participate in plasma filtration and urine excretion.
What tissue forms the layers in the stroma of the parathyroid gland?
In the parathyroid gland, layers of loose fibrous connective tissue with adipocytes and blood vessels extend inward.
What else to study on this topic
- Anatomical division of the parenchyma of lymphoid organs into zones
- Functions of myocytes in the renal fibrous capsule
- Age-related changes in the parathyroid gland and the appearance of follicle-like structures
- Steroidogenesis and features of luteal cells in the corpus luteum
- Differences between the menstrual corpus luteum and the corpus luteum of pregnancy
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