Primary follicles

VCD is ovotoxic, causing follicle destruction in both rats and mice. After 30 days of intraperitoneal dosing with 80mg/kg the number of oocyte-containing primordial and primary follicles was reduced 80% in rats and 92% in mice. 

Figure 20.3 The arrow follows the ovarian follicles (time course) from their maturation from primary follicles to the corpus luteum. (Adapted from Web site of Dr. Steven Scadding and Dr. Sandra K. Ackerley, http //www.uoguelph.ca/zoology/devobio/2101abs/ovary4.html.)...

We now turn to an anatomical description of lymph nodes. The lymph node is surrounded by a thick, fibrous capsule and is subdivided into compartments by trabeculae. Inside the capsule is the subcapsular or marginal sinus, which forms the entry point of lymphatic fluid into the node, via the afferent vessel. The lymph node cortex, which lies beneath the subcapsular sinus, is the location of the primary and secondary lymphoid follicles. The primary follicles are comprised of B-lymphocytes. An immune response stimulates B-cells to replicate and differentiate, converting the primary follicle into a secondary follicle or germinal center, surrounded by a zone of small lymphocytes. The paracortex surrounds the germinal centers and primary follicles and contains mostly T-lymphocytes. The medulla is composed of medullary cords, consisting of macrophages and plasma cells, and medullary sinuses. The medullary vessels include the arteries and veins, and the afferent and efferent lymphatic vessels, respectively, deliver the lymphatic fluid into and out of the lymph node. 

The frequency of the menstrual/estrous cycle varies among species. For example, monoestrous species (e.g., dogs, cats) exhibit 1-2 cycles per year, whereas polyes-trous species (e.g., rodents, primates) exhibit more frequent cycles of shorter duration. Primordial follicles, each consisting of an oocyte surrounded by a single layer of flattened somatic cells known as granulosa cells, are recruited to become primary follicles, a transition marked by increased oocyte size, formation of a glycoprotein matrix (zona pellucida) around the oocyte, and transformation to cuboidal-shaped... 

Q3 At the start of the cycle (which is the first day of the menstrual flow) a number of primary follicles begin to develop in the ovary, and initially oestrogen and progesterone levels are low. In the follicular phase, as the follicles develop, oestrogen levels rise considerably and ovulation occurs after 14 days when the follicle ruptures. 

Q1 The primordial follicles in which ova develop, form in the embryo and the maximal number 1-2 million, is present at birth. Follicles are located in the cortex of the ovary and each contains a primary oocyte. Following sexual maturation at puberty about 200 000 follicles remain, some of these will develop into primary follicles. During reproductive life a number of the primary follicles develop further, leading to ovulation, the remainder decline (a process known as atresia). 

A readily distinguished subtype, organized into the primary follicles of B-ceU zones focused around follicular dendritic cells in the white pulp of the spleen and the cortical areas of peripheral lymph nodes. 

Early studies of the plasticity of wool fibers revealed an apparent relationship between sulfur content and plasticity (Ripa and Speakman, 1950, 1951), but this was later shown to be fortuitous (Dry et al., 1952). Differences in plasticity of individual fibers were found to be related to their origin (Dry et al., 1952 Burley and Speakman, 1953), primary follicles producing less plastic fibers than secondary follicles. LeRoux and Speakman (1957) demonstrated a direct relationship between the diametral swelling of fibers in water or formic acid and their rate of creep. They also suggested (LeRoux and Speakman, 1955, 1957) that there is a relationship between the plasticities and the tyrosine contents of individual fibers as determined radiometrically by iodination. It was thought that tyrosine residues contribute to disorder and hence to greater plasticity in the fiber. 

The internal lymph node tissue is separated into lobes. The lobe end at the center of the node is called the medulla, whereas the wider lobe end toward the perimeter of the node is called the cortex. The lobe area just next to the cortex is called the paracortex. Surrounding the lobes is an area called the medullary sinus. T cells are concentrated in the paracortex, whereas B cells primarily are concentrated in the cortex in structures called primary follicles. Lymphocytes first travel to the medullary sinus before migrating to the cortical and paracortical regions. 

The first group, mainly children with infections, shows persistent IgA and IgM deficiency. It is unusual to see any rise in IgG with infections, this being a useful pointer to its dubious quality. Responses to tetanus, pertussis, and diphtheria vaccines are poor, although some response usually occurs in TAB. Unlike the first case described, most others have shown isohemagglutinins. Lymphocytes have been normal in numbers and in transformation to PHA. The response to dinitrofluorobenzene was normal (D2), but other delayed hypersensitivity reactions have been variable, as has homograft rejection. The lymph nodes have varied from normal through primary follicles with no germinal centers (D2), to absence... 

The ovarian changes were characterized by loss of oogonia in the primary follicles with degeneration of the inner layer of the corona. No effects in reproductive tissues were found in females following exposure to PCB 28 at 3,956 pg/kg/day PCB 77 at 892 pg/kg/day PCB 105 at 3,960 pg/kg/day ... 

CXCR5 Lack inguinal l5Tnph nodes, have small Peyer s patches, abnormal primary follicles, and lack germinal centers. B cells are diffusely distributed in T cell areas. Impaired humoral immune responses... 

Beware BCL-2 positive benign, small, primary follicles and intrafollicular T cells. 

The perinatal nodes from cynomolgus macaques contain primary follicles. T cells are centro-foUicularly positioned whereas the B cell population is located toward the periphery. Macrophages are present in the medulla and dendritic cells are present in the paracortex (Makori et al., 2003). 

Mantle cell lymphoma is a lymphoma arising from immature B-cells of the primary follicles and mantle zone of peripheral lymphoid organs, whereas the final malignant transformation seems to take place in the mature B-cell after antigen stimulation. Mantle cell lymphoma is described in the Kiel classification as centrocytic lymphoma and listed in the WHO classification as mantle cell lymphoma. This lymphoma type makes 5-10% of all lymphomas, characterized by nodular and/or diffuse proliferation of small to medium sized neoplastic lymphoid cells with coexpression of B-cell-associated antigens and CD5. Mantle cell lymphoma occurs mainly in older adults with a high male female ratio and shows low sensitivity to chemotherapy with a median survival less than 5 years. 

Fig. 2. Part of an oocyte (primary follicle) of a dog. Numerous mitochondria in close contact with the endoplasmic reticulum (i). Follicle epithelium (F), basal membrane (B), collagen fibrils of the connective tissue (X). 1 8,500.

D) Mitochondrion with cristae, tubuli, and vesicles. Interstitial cell (Leydig cell) of the differentiated rat testis. Close spatial relationship with the endoplasmic reticulum (X). 1 36,000. (E) Mitochondrion with few cristae arranged in a typical way and fine granular matrix. Oocyte of a primary follicle (rabbit). 1 36,000. (F). Mitochondria with numerous tubuli and vesicles and with an electron dense matrix. Zona fasciculata of the suprarenal gland (adult rat). 1 36,000,... 

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