The Normal, Cryptorchid and Retractile Prepuberal Human Testis: A Comparative Morphometric Ultrastructural Study of 101 Cases

Fifty-two surgical biopsies from retractile testes of patients in pediatric age (3-14 years), of which 25 were treated with hormonal therapy (RT) and 27 did not undergo therapy before orchidopexy (RNT), were compared with the biopsies of 19 normal (N) and 30 cryptorchid or ectopic (E) testes. A light and electron microscopic morphologic and morphometric study was performed. For the quantitative investigation 4 parameters were selected: a) the mean tubular diameter (on 20 cross-sections); b) the mean spermatogonial number per tubular section; c) the mean nucleolar area of the Sertoli cells; and d) the mean thickness of the tubular basal lamina. The 101 biopsies were collected for statistical evaluation into four age groups: 3-6 years, 7-10, 11-13 without spermatogenesis and 10-14 with signs of early spermatogenesis. In the RT category the mean tubular diameter and the mean spermatogonial number were similar to N in the first two age groups, but were significantly reduced in the RNT categories. The morphometric study of the Sertoli cell nucleolar area confirms the delay of maturation observed in the categories of RT, RNT and E. In normal biopsies, the basal lamina shows a progressive reduction of the thickness, with the lowest values around puberty, while constantly higher values were found in the other categories, although this increase is not statistically significant

Muscle and adipose tissue morphology, insulin sensitivity and beta-cell function in diabetic and nondiabetic obese patients: effects of bariatric surgery

Obesity is characterized by insulin-resistance (IR), enhanced lipolysis, and ectopic, inflamed fat. We related the histology of subcutaneous (SAT), visceral fat (VAT), and skeletal muscle to the metabolic abnormalities, and tested their mutual changes after bariatric surgery in type 2 diabetic (T2D) and weight-matched non-diabetic (ND) patients. We measured IR (insulin clamp), lipolysis ((2)H5-glycerol infusion), ß-cell glucose-sensitivity (ß-GS, mathematical modeling), and VAT, SAT, and rectus abdominis histology (light and electron microscopy). Presurgery, SAT and VAT showed signs of fibrosis/necrosis, small mitochondria, free interstitial lipids, thickened capillary basement membrane. Compared to ND, T2D had impaired ß-GS, intracapillary neutrophils and higher intramyocellular fat, adipocyte area in VAT, crown-like structures (CLS) in VAT and SAT with rare structures (cyst-like) ~10-fold larger than CLS. Fat expansion was associated with enhanced lipolysis and IR. VAT histology and intramyocellular fat were related to impaired ß-GS. Postsurgery, IR and lipolysis improved in all, ß-GS improved in T2D. Muscle fat infiltration was reduced, adipocytes were smaller and richer in mitochondria, and CLS density in SAT was reduced. In conclusion, IR improves proportionally to weight loss but remains subnormal, whilst SAT and muscle changes disappear. In T2D postsurgery, some VAT pathology persists and beta-cell dysfunction improves but is not normalized

Dynamic regulation of genes involved in mitochondrial DNA replication and transcription during mouse brown fat cell differentiation and recruitment.

BACKGROUND: Brown adipocytes are specialised in dissipating energy through adaptive thermogenesis, whereas white adipocytes are specialised in energy storage. These essentially opposite functions are possible for two reasons relating to mitochondria, namely expression of uncoupling protein 1 (UCP1) and a remarkably higher mitochondrial abundance in brown adipocytes. METHODOLOGY/PRINCIPAL FINDINGS: Here we report a comprehensive characterisation of gene expression linked to mitochondrial DNA replication, transcription and function during white and brown fat cell differentiation in vitro as well as in white and brown fat, brown adipose tissue fractions and in selected adipose tissues during cold exposure. We find a massive induction of the majority of such genes during brown adipocyte differentiation and recruitment, e.g. of the mitochondrial transcription factors A (Tfam) and B2 (Tfb2m), whereas only a subset of the same genes were induced during white adipose conversion. In addition, PR domain containing 16 (PRDM16) was found to be expressed at substantially higher levels in brown compared to white pre-adipocytes and adipocytes. We demonstrate that forced expression of Tfam but not Tfb2m in brown adipocyte precursor cells promotes mitochondrial DNA replication, and that silencing of PRDM16 expression during brown fat cell differentiation blunts mitochondrial biogenesis and expression of brown fat cell markers. CONCLUSIONS/SIGNIFICANCE: Using both in vitro and in vivo model systems of white and brown fat cell differentiation, we report a detailed characterisation of gene expression linked to mitochondrial biogenesis and function. We find significant differences in differentiating white and brown adipocytes, which might explain the notable increase in mitochondrial content observed during brown adipose conversion. In addition, our data support a key role of PRDM16 in triggering brown adipocyte differentiation, including mitochondrial biogenesis and expression of UCP1

Dynamic regulation of genes involved in mitochondrial DNA replication and transcription during mouse brown fat cell differentiation and recruitment

none9noneMURHOLM M; DIXEN K; QVORTRUP K; HANSEN LH; AMRI EZ; MADSEN L; G. BARBATELLI; QUISTORFF B; HANSEN JBMurholm, M; Dixen, K; Qvortrup, K; Hansen, Lh; Amri, Ez; Madsen, L; Barbatelli, Giorgio; Quistorff, B; Hansen, J

High-Fat Diet Impairs Mouse Median Eminence: A Study by Transmission and Scanning Electron Microscopy Coupled with Raman Spectroscopy

Hypothalamic dysfunction is an initial event following diet-induced obesity, primarily involving areas regulating energy balance such as arcuate nucleus (Arc) and median eminence (ME). To gain insights into the early hypothalamic diet-induced alterations, adult CD1 mice fed a high-fat diet (HFD) for 6 weeks were studied and compared with normo-fed controls. Transmission and scanning electron microscopy and histological staining were employed for morphological studies of the ME, while Raman spectroscopy was applied for the biochemical analysis of the Arc-ME complex. In HFD mice, ME β2-tanycytes, glial cells dedicated to blood-liquor crosstalk, exhibited remarkable ultrastructural anomalies, including altered alignment, reduced junctions, degenerating organelles, and higher content of lipid droplets, lysosomes, and autophagosomes. Degenerating tanycytes also displayed an electron transparent cytoplasm filled with numerous vesicles, and they were surrounded by dilated extracellular spaces extending up to the subependymal layer. Consistently, Raman spectroscopy analysis of the Arc-ME complex revealed higher glycogen, collagen, and lipid bands in HFD mice compared with controls, and there was also a higher band corresponding to the cyanide group in the former compared to the last. Collectively, these data show that ME β2-tanycytes exhibit early structural and chemical alterations due to HFD and reveal for the first-time hypothalamic cyanide presence following high dietary lipids consumption, which is a novel aspect with potential implications in the field of obesity

Brown adipose tissue whitening leads to brown adipocyte death and adipose tissue inflammation

In mammals, white adipose tissue (WAT) stores and releases lipids, whereas brown adipose tissue (BAT) oxidizes lipids to fuel thermogenesis. In obese individuals, WAT undergoes profound changes; it expands, becomes dysfunctional, and develops a low-grade inflammatory state. Importantly, BAT content and activity decline in obese subjects, mainly as a result of the conversion of brown adipocytes to white-like unilocular cells. Here, we show that BAT "whitening" is induced by multiple factors, including high ambient temperature, leptin receptor deficiency, \u3b2-adrenergic signaling impairment, and lipase deficiency, each of which is capable of inducing macrophage infiltration, brown adipocyte death, and crown-like structure (CLS) formation. Brown-to-white conversion and increased CLS formation were most marked in BAT from adipose triglyceride lipase (Atgl)-deficient mice, where, according to transmission electron microscopy, whitened brown adipocytes contained enlarged endoplasmic reticulum, cholesterol crystals, and some degenerating mitochondria, and were surrounded by an increased number of collagen fibrils. Gene expression analysis showed that BAT whitening in Atgl-deficient mice was associated to a strong inflammatory response and NLRP3 inflammasome activation. Altogether, the present findings suggest that converted enlarged brown adipocytes are highly prone to death, which, by promoting inflammation in whitened BAT, may contribute to the typical inflammatory state seen in obesity