Types Of Pigment Granules Research Articles

Presence of pigment in the ovine pineal gland during embryonic development.

Light- and electron-microscopic analyses were used to identify and describe the characteristic features of cells containing pigment in the ovine pineal gland during prenatal development. 72 ovine embryos (36 male, 36 female) ranging in age from 54 to 150 days were used for this study. Cells containing pigment granules were a constant feature in this gland. When samples from the different groups were inspected using the naked eye, the detection of pigment was of 61% in groups I (54 to 67 days of prenatal development) and II (71 to 92 days of prenatal development), 83% in group III (98 to 113 days of prenatal development) and 25% in group IV (118 to 150 days of prenatal development). The morphological features and histochemical properties of the pineal pigment enabled it to be identified as melanin. Several types of pigment granules were ultrastructurally distinguished; these varied in size, shape and location within pineal cell populations. The pigment granules were detected in pinealocytes, interstitial cells and pigmented cells. The largest amount and the widest variety of pigmented granules were found in pigmented cells. The presence of cells containing pigmented granules amongst the cell populations of the developing ovine pineal gland was analysed and compared with that of other mammalian species.

Body Colouration Related to the Deposition of Pteridines in the Epidermis and Other Organs of Dysdercus Species (Insecta; Heteroptera: Pyrrhocoridae)

In epidermal cells of Dysdercus species, two types of pigment granules were detected using both light and electron microscopic methods; the granules differed in colour, size, distribution and osmiophily. Red (D. intermedius) and yellow (D. nigrofasciatus) epidermal cells contained both types of granules, but in white cells only one type was present. Chromatographic analyses showed that the larger granules were more transparent to electrons, and contained uric acid, while the smaller ones contained erythropterin, became coloured later, and were osmiophilic. In accordance with these findings, in the testes of D. intermedius both granule types were present, but in the testes of D. nigrofasciatus only those containing erythropterin. The number of granules per cell varied with the species and developmental stage. Epidermal cells of D. intermedius contained more erythropterin granules than those of D. nigrofasciatus, the reverse occurring in the testes. This pattern corresponded to the visible colouration of the insects. As the development progressed, a decrease of the red and an increase of the white granules took place in the coloured epidermal cells. The main amount of pteridines, except isoxanthopterin, was accumulated in the integument of the insects studied. Chemical and histological data showed the influence of pterins on insect colouration. Orange, yellow and red colours were caused by different amounts of erythropterin containing special granules in the epidermal cells, and the white colour only by uric acid containing granules. A partial melanization of the cuticle resulted in dark spots below which pteridines were deposited additionally in the epidermal cells. Considering erythropterin, the quantitative chemical data are in accordance with the histological ones and also with the colouration externally visible. Intensively red coloured stages had a higher concentration of erythropterin and more corresponding granules than the light-red coloured ones; the lowest amount was found in yellow coloured insects. Therefore, the pigmentation effect of erythropterin, which reached from yellow to orange and red, depended on its concentration and played the most important role in the colouration of the Dysdercus species studied, uric acid was responsible for the colouration of the white parts of the integument.

A topography and ultrastructural characterization of in vivo 5,7-dihydroxytryptamine-labeled serotonin-containing neurons in the central nervous system of Aplysia californica.

1. Several weeks after administration of 5,7-dihydroxytryptamine (5,7-DHT) to Aplysia, a dark pigmentation appears in serotonin-containing neurons, and this pigmentation allows visual identification of serotonergic neurons but does not appear to alter their physiology. 2. We have determined the distribution of labeled nerve cell bodies in the various ganglia of Aplysia and have characterized the pigment containing structures in both control and labeled neurons. 3. All neurons in this preparation, whether or not they utilize serotonin as a transmitter, contain pigment granules, and three types of pigment granules can be distinguished. After 5,7-DHT a new type of granule appears in serotonergic neurons, probably reflecting lysosomes that have accumulated serotonergic synaptic vesicles that contain the oxidized 5,7-DHT. 4. It remains unclear why this substance does not cause neurotoxicity in mollusks as it does in mammalian preparations.

Ultrastructural Study of an Endosymbiotic Alga and Its Host Ciliate Stentor niger

ABSTRACTStentor niger collected in the suburbs of Hiroshima contained in its cytoplasm several hundreds of endosymbiotic algae and innumerable brownish pigment granules. The body of the ciliate was dark due to a mixture of the green endosymbiotic algae and brown pigment granules. The algae belonged to the genus Chlorella; each was enclosed in a perialgal vacuole and dispersed uniformly in the host cytoplasm from the myoneme layer inward to the center of the ciliate. The cell wall and plasma membrane of the alga enclosed a nucleus, chloroplast, mitochondrion, Golgi complex, accumulation bodies, myelinated vesicles, and many ribosomes. The chloroplast occupied more than half of the volume of the alga and contained a conspicuous pyrenoid. Algal multiplication occurred by two successive divisions of an alga, leading to four autospores within a perialgal vacuole; the walls of the vacuole invaginated to separate the autospores each into its own vacuole. Three types of pigment granules were scattered uniformly throughout the cytoplasm of the ciliate. The ultrastructure of the membranellar region, somatic cortex, and macro‐ and micronucleus of the ciliate are also described.

Ultrastructure of the chromatophores of Palaemon affinis Heilprin (crustacea: decapoda). The structural basis of pigment migration

The relationships between pigment granules and the prominent smooth endoplasmic reticulum in the chromatophores of the shrimp, Palaemon affinis Heilprin, were investigated by transmission electron microscopy. Different types of pigment granules within the chromatophores were found to exhibit a close structural continuity with the cisternal membranes. The membranes of membrane-bound pigment granules were seen to be continuous with those of the ER cisternae, while pigment granules lacking membranes appear to adhere to the external cisternal surfaces. The reticulum, which seems to form a network enmeshing the pigment granules, is proposed to be part of a continuum linking these granules with their translocating force.

Ultrastructure of the extracutaneous pigment cells in the plaice (Pleuronectes platessa, L., Teleostei)

The extracutaneous pigment cell system of the plaice (Pleuronectes platessa L.) was examined by light and electron microscopy in selected regions, including two cutaneous regions for comparison. The extracutaneous pigmentation consists of guanocytes and melanocytes with differing distributions within the body. The eyeless side lacks melanocytes. The pigment cells are differentiated as very flat elements with long processes. They display an affinity for loose connective tissue at boundary layers such as the peritoneal epithelium, organ capsules or blood vessels, to which they are parallelly arranged at a very constant distance. In some locations guanocytes are intimately associated with melanocytes forming "reduced chromatophore units". Extracutaneous pigment cells are poor in mitochondria, endoplasmic reticulum, microfilaments, caveolae intracellulares, ribosomes and glycogen granules, all of which are more abundant in cutaneous pigment cells and pigment cells of the eye. In extracutaneous guanocytes the crystals are loosely arranged parallel to the cell surface, in cutaneous guanocytes perpendicular. Cells with rod-like vesicular cisternae are described as "guanoblasts". No single pigment cell was found exhibiting different types of pigment granules. The varying colors of extracutaneous pigmentation arise from varying combinations of guanocytes and melanocytes in addition to the color of the tissue itself.

Age-associated changes in the hypothalmus of the guinea pig: Effect of dimethylaminomethyl p-chlorophenoxycyaacetate microscopic and histochemical study

Contrary to the earlier light microscopic studies, electron microscopic investigation on 11 male guinea pigs revealed marked accumulation of lipofucsin pigment in the hypothalamic neurons with the passage of time. Even in 6 month guinea pigs scattered pigment bodies were noted. Two types of pigment granules have been observed in the aged animals. Dimethylaminoethyl p-chlorophenoxyacetate caused a marked diminution of the electron density and reduction in the size and number of the pigment granules. Furthermore, histochemical examination revealed a marked diminution of acid phosphatase activity in the treated group of animals as compared to normal “control”. But the α-esterase and succinic dehydrogenase activity was found to be increased following drug treatment.

Morphology of the eyespot and description of two pigment granules in the esophageal muscle of a marine nematode, Oncolaimus vesicarius

Two types of pigment granules in esophageal muscle cells are compared in the light and the electron microscope. The dark-reddish “eyespot granules” are located only in the anteriormost radial muscle cell and are highly concentrated anterolaterally in the cell, forming the eyespots. The paler greenish “esophageal granules” are found in other radial muscle cells and in the marginal muscle cells. In addition to their color and location, the two granules are distinguishable by their fine structure. The morphology of the eyespot suggests that the eyespot of this species is not a photoreceptor, as previously supposed. Evidence is discussed which indicates that the eyespot may function to shade a possible light-sensitive structure in an adjacent enlargement of the amphidial organ.

The development of pigment granules in the eyes of wild type and mutant Drosophila melanogaster.

The eye pigment system in Drosophila melanogaster has been studied with the electron microscope. Details in the development of pigment granules in wild type flies and in three eye color mutants are described. Four different types of pigment granules have been found. Type I granules, which carry ommochrome pigment and occur in both primary and secondary pigment cells of ommatidia, are believed to develop as vesicular secretions by way of the Golgi apparatus. The formation of Type II granules, which are restricted to the secondary pigment cells and contain drosopterin pigments, involves accumulation of 60- to 80-A fibers producing an elliptical granule. Type III granules appear to be empty vesicles, except for small marginal areas of dense material; they are thought to be abnormal entities containing ommochrome pigment. Type IV granules are characteristic of colorless mutants regardless of genotype, and during the course of development they often contain glycogen, ribosomes, and show acid phosphatase activity; for these reasons and because of their bizarre and variable morphology, they are considered to be autophagic vacuoles. The 300-A particles commonly found in pigment cells are identified as glycogen on the basis of their morphology and their sensitivity to salivary digestion.