Medial Mamillary Nucleus


Similar changes were noted in the medial mamillary nucleus and in the hippocampus that are involved in the regulation of learning and memory.  

Previously we have reported an increased nuclear estrogen receptor-alpha (ERalpha) in the medial mamillary nucleus (MMN) in Alzheimer's disease (AD).  

the supraoptic nucleus (SON), the infundibular nucleus (INF), the medial mamillary nucleus (MMN).  

The morphology, distribution and relative frequency of GABAergic neurons in the medial mamillary nucleus (MMN) of normal human individuals was studied using a glutamic acid decarboxylase (GAD) antiserum.  

Women revealed more nuclear ER beta-ir than men of a low to intermediate level, e.g., in the suprachiasmatic, supraoptic, paraventricular, infundibular, and medial mamillary nucleus.  

The medial mamillary nucleus (MMN) is situated caudally in the human hypothalamus and is involved in memory processes.  

A strong sex difference, with more nuclear ERalpha-ir in women, was observed rostrally in the diagonal band of Broca and caudally in the medial mamillary nucleus. ERalpha-ir in T1, S2, and S8 suggested that most of the observed sex differences in ERalpha-ir are "activational" (e.g., ventromedial nucleus/medial mamillary nucleus) rather than "organizational." Species similarities and differences in ERalpha-ir distribution and possible functional implications are discussed..  

The spiny cells, both cap-like and fusiform ones, were observed preponderantly, in the medial mamillary nucleus, whereas in the lateral mamillary nucleus there were mainly seen the triangular and fusiform neurones, either spiny or aspiny cells.  

In men, intense nuclear AR-ir was found in neurons of the horizontal limb of the diagonal band of Broca, in neurons of the lateromamillary nucleus (LMN), and in the medial mamillary nucleus (MMN).  

Direct frontomamillary ways from these cortical areas terminate basically in medial mamillary nucleus.  

In the light microscopic studies, injections of WGA-HRP into the rostromedial pontine nuclei produced dense, retrograde labeling both in the dorsal peduncular area of the medial prefrontal cortex and in the medial mamillary nucleus, pars medialis.  

D3 receptors appeared at postnatal day 4 in the nucleus accumbens, at postnatal day 8 in the substantia nigra, in the medial mamillary nucleus and in the anterior thalamic complex, and at postnatal day 11 in the archaeocerebellum.  

These injections resulted in a marked increase in Fos-like immunoreactivity ipsilaterally in both the medial mamillary nucleus and in its principle thalamic projection targets, the anteroventral and anteromedial thalamic nuclei.  

There were no labeled cells traced to the medial mamillary nucleus.  

Morpho-functional state of the medial mamillary nucleus of the posterior hypothalamus in patients who had died from various diseases at the age of 18 to 80 years were studied by methods of quantitative histochemistry on the material of early necropsies.  

Injections of WGA-HRP into the medial mamillary nucleus resulted in dense anterograde and retrograde labeling in the ventral tegmental nucleus, while injections in the lateral mamillary nucleus resulted in dense anterograde labeling in the dorsal tegmental nucleus pars dorsalis and dense anterograde and retrograde labeling in the pars ventralis of the dorsal tegmental nucleus. The anterograde labeling in these two precerebellar relay nuclei was distributed near the midline such that projections from the lateral mamillary nucleus terminated mainly dorsomedial to the terminal fields of projections from the medial mamillary nucleus.  

Projections from the rostrodorsal and caudoventral subiculum terminated in a topographically organized laminar fashion in the medial mamillary nucleus bilaterally, whereas afferent projections from the presubiculum and parasubiculum terminated only in the lateral mamillary nucleus. Injections of tracer into these brain regions gave rise to dense labeling of axon terminals in the medial mamillary nucleus, pars medianus, and in the anterior dorsomedial portion of the pars medialis. Projections from the dorsal tegmental nucleus terminated in the ipsilateral lateral mamillary nucleus, whereas afferent projections from the anterior and posterior subnuclei of the ventral tegmental nucleus terminated topographically in the medial mamillary nucleus.  

Following implantations of HRP-WGA ventromedially in rostral parts of the pontine nuclei, 22-44% of all labeled cells in the brainstem and diencephalon are found in the medial mamillary nucleus ipsilateral to the implantation. Following implantations of HRP-WGA in restricted parts of the hypothalamus, fibers from the medial mamillary nucleus were found to terminate ventromedially at all rostrocaudal levels of the pontine nuclei, ipsilateral to the implantation. In two cases with small implantations of HRP-WGA ventromedially in rostral parts of the pontine nuclei, labeled cells are found both in the medial mamillary nucleus and the cingulate gyrus. Thus, it seems possible that fibers from the medial mamillary nucleus and the cingulate gyrus converge upon a restricted area ventromedially in rostral parts of the pontine nuclei..  

Neurons containing preproenkephalin mRNA were found in the piriform cortex, ventral tenia tecta, several regions of the neocortex, nucleus accumbens, olfactory tubercle, caudate-putamen, lateral septum, bed nucleus of the stria terminalis, diagonal band of Broca, preoptic area, amygdala (especially central nucleus, with fewer labeled neurons in all other nuclei), hippocampal formation, anterior hypothalamic nucleus, perifornical region, lateral hypothalamus, paraventricular nucleus, dorsomedial and ventromedial hypothalamic nuclei, arcuate nucleus, dorsal and ventral premamillary nuclei, medial mamillary nucleus, lateral geniculate nucleus, zona incerta, periaqueductal gray, midbrain reticular formation, ventral tegmental area of Tsai, inferior colliculus, dorsal and ventral tegmental nuclei of Gudden, dorsal and ventral parabrachial nuclei, pontine and medullary reticular formation, several portions of the raphe nuclei, nucleus of the solitary tract, nucleus of the spinal trigeminal tract (especially substantia gelatinosa), ventral and dorsal cochlear nuclei, medial and spinal vestibular nuclei, cuneate and external cuneate nuclei, gracile nucleus, superior olive, nucleus of the trapezoid body, some deep cerebellar nuclei, Golgi neurons in the cerebellum, and most laminae of the spinal cord.  

Additional experiments showed that more selective lesions in either the anterior medial thalamus (AMT), the posterior medial thalamus (PMT), or the medial mamillary nucleus (MB) only produced mild recognition memory impairments.  

Cynomolgus monkeys with complete bilateral destruction of the medial mamillary nucleus exhibited little, if any, deficit in object recognition, although they did show evidence of impairment in spatial memory.  

The medial mamillary nucleus was divided on the basis of the cytoarchitecture into four subnuclei: the pars medialis centralis, pars medialis dorsalis, pars lateralis, and pars basalis.  

Although the medial mamillary nucleus does not project to the amygdala, there is evidence for a minor projection from the supramamillary region to the medial amygdaloid nucleus.  

The medial mamillary nucleus was found to project through the mamillothalamic tract to the ipsilateral anteroventral, anteromedial, and interanteromedial nuclei, and by way of the mamillotegmental tract principally to the deep tegmental nucleus (of Gudden).  

The nuclei identified include: the medial mamillary nucleus (in which at least three distinct subdivisions can be recognized--a pars medialis, a pars lateralis, and a pars basalis); the small-celled nucleus intercalatus; the large-celled lateral mamillary nucleus; a single premamillary nucleus; the tuberomamillary nucleus; the posterior hypothalamic nucleus; the caudal extension of the lateral hypothalamic area; the supramamillary area; and the paramamillary nucleus (which appears to correspond to the nucleus of the ansa lenticularis of other workers).  

Variability has been stated in the formation of the medial mamillary nucleus.  

The medial mamillary nucleus is clearly divided into several parts. The nucleus mamillaris lateralis is poorly developed, but can be identified lying between the lateral part of the medial mamillary nucleus and the nucleus intercalatus.  

The specific afferents (RL-boutons)--originating from the medial mamillary nucleus--are presynaptic to both relay cell dendrites and "presynaptic" dendrite profiles of Golgi type II interneurons, which in turn are presynaptic to the same relay dendrites (synaptic triads).  

The medial mamillary nucleus of cattle is with an average volume of 47.7 mm3 the largest nucleus of the mamillary body.  

PK was significantly elevated in the lateral preoptic and suprachiasmatic nuclei of the anterior hypothalamus and also in the medial mamillary nucleus and median eminence.  


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